Mega Peanut Butter Swirl Brownies

stack of 3 peanut butter swirl brownies

Can you believe I’ve never shared a peanut butter swirl brownie recipe on my blog before?

Actually, wait. I did share a *skinnier* version about 5 years ago that’s made with zero flour, a blender, Greek yogurt, and oats. Sounds very strange, but it totally works. By the way, I’ve since made them with coconut sugar and they’re SO GOOD.

peanut butter swirl brownies cut into squares

We’re not on a diet today. This is the real deal. The obnoxiously fudgy dense brownies completely overloaded with chocolate and swirled with an awesomely rich peanut butter filling and– wait for it– filled with chopped peanut butter cups. If you listen closely, you can hear your bikini running away in fright.

I label them “mega” because they’re one of the richest desserts to come out of my oven. The base of the brownies is this homemade brownie recipe, though I add a little more chocolate. If you’ve tried that brownie recipe before, you can imagine how “mega” the peanut butter swirl version is!

I made the first batch of mega peanut butter swirl brownies nearly a month ago when our friends came to visit. I knew neither Kevin nor I could be trusted with an entire batch just to ourselves and I’m going to warn you now– make sure you’ve got company coming over or a large group to help you snack on these! Self control seems to run for the hills. Maybe it’s hanging out with our bikinis.

So here’s how we’re going to make them…

brownie batter in a glass bowl with chopped peanut butter cups

Whip up the homemade brownie batter. That’s easy. Curious about the ingredients and why each is important? Here’s that post you can review.

Add chopped peanut butter cups. ♥

Prepare the epic PB swirl next. There’s a lot of it because we want mega peanut butter swirls in every single bite. Clearly, we’re not skimping on anything today.

Only 4 ingredients needed for the peanut butter swirl: creamy peanut butter, confectioners’ sugar, butter, and vanilla extract– pretty much the same ingredients we use for peanut butter balls, too. You’re using butter and vanilla in the brownie recipe anyway, so really it’s just 2 additional ingredients. The easiest way to combine them all is using a mixer.

peanut butter swirl mixture in a glass bowl with a hand mixer

How to Perfect the Swirl

Since we’re making a super mega dessert, we want to make sure it looks pretty darn good too. The swirling part is an art, but one you can easily master on the first try. All you do is randomly drop spoonfuls of brownie batter and spoonfuls of peanut butter batter into the lined brownie pan. It’s going to be super haphazard like so:

scoops of brownie batter and peanut butter swirl mixture in a baking pan lined with parchment paper

Save a couple spoonfuls of brownie batter to fill in any gaps or cover any heavy peanut butter sections. Then take a knife and run it up and down both horizontally and vertically, creating swirls of the two batters like so:

peanut butter mixture and brownie batter swirled together in a baking pan

Easy stuff, right? Sprinkle the pan with a couple leftover chopped peanut butter cups and pop into the oven.

This brownie recipe, without the peanut butter swirl, takes about 30-32 minutes. The peanut butter swirl adds a couple minutes to the bake time. But I urge you to watch the brownies themselves– not the clock. The bake time is simply a guideline and you shouldn’t be surprised or alarmed if the brownies take longer or shorter. You’ll know the brownies are done when the top looks set. Test them using a toothpick. If there is wet batter on the toothpick, the brownies need more time. If there are a few moist crumbs on the toothpick, the brownies are done. If the toothpick is clean, the brownies are overdone. So keep your eyes on these!

overhead image of peanut butter swirl brownies

How to Neatly Cut Brownies

Another art you can master on the first try!

  1. Wait until the brownies have completely cooled. What a buzzkill. But this helps ensure some neatly sliced fudgy brownies! I always stick the slightly cooled pan in the fridge for an hour or so to speed up the process.
  2. Use a plastic knife. One of those dinky ones you buy for potlucks and picnics. SO WEIRD, right? But a plastic knife strangely keeps layered or swirled brownies neat. It’s my little trick for neatly cut mint chocolate brownies. If you don’t have one and really don’t feel like getting one, just use a very sharp knife.
  3. Whichever knife you use, wipe it clean with a paper towel between each cut.

That’s all, folks!

peanut butter swirl brownie

My last piece of advice: have a mega glass of milk handy. Or at least some sweatpants.

Print
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peanut butter swirl brownie

Mega Peanut Butter Swirl Brownies

  • Author: Sally
  • Prep Time: 20 minutes
  • Cook Time: 35 minutes
  • Total Time: 3 hours, 20 minutes
  • Yield: 18-24 brownies
  • Category: Brownies
  • Method: Baking
  • Cuisine: American

Description

These mega peanut butter swirl brownies are unapologetically rich and fudgy! This homemade brownie recipe is one of my favorites and so easy to make.


Ingredients

  • 1 cup (16 Tbsp; 2 sticks; 230g) unsalted butter, divided
  • one 4 ounce (113g) semi-sweet chocolate bar, coarsely chopped*
  • 2 cups (400g) granulated sugar
  • 3 large eggs, at room temperature
  • 2 teaspoons pure vanilla extract, divided
  • 1 cup (82g) unsweetened natural or dutch-process cocoa powder*
  • 1 cup (125g) all-purpose flour (spoon & leveled)
  • 1 teaspoon salt
  • 1 and 1/2 cups chopped peanut butter cups
  • 1 cup (250g) creamy peanut butter*
  • 1/2 cup (60g) confectioners’ sugar

Instructions

  1. Preheat the oven to 350°F (177°C) and grease a 9×13 inch pan or line with aluminum foil or parchment paper, leaving an overhang on the sides to lift the finished brownies out (makes cutting easier!). Set aside.
  2. Brownie batter: In a microwave-safe bowl, combine 3/4 cup butter (12 Tbsp; 1 and 1/2 sticks) and chopped chocolate. Melt in 30 second increments, whisking after each, until completely smooth. Whisk in the granulated sugar until completely combined, then whisk in the eggs and 1 teaspoon vanilla. The batter will be light brown and a little dull looking.
  3. Add the cocoa powder, flour, and salt. Fold it all together with a rubber spatula or wooden spoon. Batter will be very thick. Stir in chopped peanut butter cups, reserving a small handful to sprinkle on top. Set aside.
  4. Peanut butter swirl: Melt the remaining butter. Using a hand-held or stand mixer fitted with a paddle or whisk attachment, beat the melted butter, remaining 1 teaspoon of vanilla, the peanut butter, and confectioners’ sugar until smooth. Drop big spoonfuls of most of the chocolate batter randomly into the prepared pan– see photo above for a visual. Top with random spoonfuls of all of the peanut butter batter. Drop random spoonfuls of remaining chocolate batter over any bare spots or heavy peanut butter spots. Using a knife, swirl the batters together. The brownie batter is pretty thick, so do your best. Sprinkle with any leftover peanut butter cups.
  5. (See note about how to tell if brownies are done in the post above.) Bake for 30 minutes, then test the brownies with a toothpick. Insert it into the center of the pan. If it comes out with wet batter, the brownies are not done. If there are only a few moist crumbs, the brownies are done. Keep checking every 2 minutes until you have moist crumbs. My brownies take 33-36 minutes.
  6. Remove from the oven and place on a wire rack to cool completely before cutting into squares. Cover and store leftover brownies at room temperature for up to 1 week.

Notes

  1. Make Ahead Instructions: Brownies freeze well up to 3 months. Thaw overnight in the refrigerator then bring to room temperature before serving.
  2. Chocolate Bars: Chocolate bars are typically sold in 4 ounce bars. I suggest Ghirardelli, Baker’s brand, or Lindt. Do not use chocolate chips.
  3. Cocoa Powder: You can use either natural or dutch-process cocoa powder. I prefer dutch-process for a smoother flavor.
  4. Peanut Butter:Use a generic creamy peanut butter like Jif or Skippy. Crunchy could work too. Do not use natural, homemade, or super oily brand as the swirl will not set up properly.

Here’s that older recipe for the skinny version!

stack of 2 peanut butter chocolate brownies

48 Comments

  1. Paula Jarrett says:

    Awesome recipe!! The plastic knife has been my trick for years now!! I first started using one though because I figured it was the best thing to use to avoid making scratch marks in my (non-stick) type pans!! I have baking pans that are now 20 yrs old without a single scratch because of this little trick!!

  2. I made these Monday night and they were AMAZING!!!!!!!!!!!!! Everyone that has tried them LOVES them too. Def my new go to brownie recipe but I couldn’t make them look as pretty as yours. My top was just kinda a PB blob. I’ll keep trying but Sally you’re the best!!!!!!!!!

  3. Been waiting all week to make them and they didn’t disappoint!  I undercook my brownies a teeny bit because we like them soft and gooey.  Only my dog was sad because she couldn’t have any.  I’ll make the raspberry swirl pound cake next so she can have some.  I’ve only recently found your blog and it’s the best!

  4. These brownies were a HUGE hit at the cookout I went to yesterday. Thanks for another great recipe!

  5. Absolutely delicious!  I have made the PB stuffed brownies, and the “healthy” PB, but these are my favorite!  The PB cups melted into the batter, and just added peanut butter goodness.  Thanks for another awesome recipe, Sally!  Your site is my favorite.  Thanks for sharing your genius with us!  

  6. Donna Hall says:

    I have never left a review or even a comment for a recipe before but I was compelled to leave one for these brownies because they are simply over the top, out of this world delicious.  Sally, yours is my favorite website when I’m looking to treat my family – or take a sure fire hit dessert to an event.  You never miss.  Thank you so much!  Keep the awesome recipes coming!  

  7. Sally which ones do you like better? These or the peanut butter stuffed brownies? I’m having a hard time deciding which recipe to bake. 🙂

    1. Hmm. Both are wonderful and practically taste the same 🙂 These may be a little more dense (if that’s possible). This recipe also makes a larger batch while the peanut butter stuffed brownies are baked in a 9×9 pan.

  8. I tried making these and followed ingredients and instructions to the letter. They didn’t set in the middle, toothpick kept coming out caked in better. Eventually left them in so long the peanut butter cup chunks on top burnt and STILL the middle was goo. Really disappointed. They just don’t seem to have enough flour in them. And 400g of sugar seems an awful lot.

  9. Hi Sally! Can I swap out peanut butter cups for chopped up Oreos? Wanted to make Oreo peanut butter brownies!

    1. Sure can! Yum!

  10. I just made these and had the same problem as another reviewer. They were in the oven for an hour and still had batter coming out on the toothpick, but the edges were starting to burn. I’m not sure what the problem is, but do agree, I felt like 2 cups of sugar was a lot. Is that what everyone else used??

    1. Hi Jill! My recommendation is to lower the oven temperature, lower the oven rack, and tent with aluminum foil after about 25 minutes. The bake time will be extended, but the brownies should bake more evenly.

  11. I can’t wait to try these! Before I shop for the ingredients, how many peanut butter cups do you need for one recipe?

    1. Hi Susan! I’ve never counted how many peanut butter cups, but I suggest buying a bag of the minis and chopping them up until you reach 1 and 1/2 cups.

  12. I’m totally loving how you can freeze most of your bars. I’m planning to make your pumpkin pie bars, white chocolate snickerdoodle bars and these for two parties that I have that are a couple weeks apart. Do you suggest cutting the bars first or leaving together. I’m a new cook and love all your recipes and videos!

    1. Hi Bridget! This is a GREAT question and I recommend freezing the bars already cut. It’s just so much easier that way. They thaw perfectly and are already cut, so just plate and serve them.

  13. Just wanted to let my gluten free friends know that i tried this recipe with gluten free flour and it worked wonderfully! Thank you, so delicious!!!

  14. These were AMAZINGly delicious and fudgy and moist. I would just suggest putting a layer of brownie batter down first before adding the peanut butter dollops; the peanut butter has no real binder so it tends to crumble at any point where it’s just the PB mixture.

  15. Hi Sally! For the peanut butter swirl, can i just use the peanut butter itself by microwave it and omit the confectioners sugar just to reduce the sweetness level.

    1. You can, yes, but the peanut butter (by itself) melts a little bit into the batter.

  16. I through these together really quickly tonight halving the recipe for a few girl friends that were coming over. I was thinking they were going to be good but was not expecting too much of them but everyone loved them. Now my friends are huge peanut butter chocolate fans but let be honest who isn’t. Thanks so much 🙂

  17. I really wanted peanut butter swirl brownies, but these were a bit too “mega” for my family. None of us are crazy about desserts and we tend to dislike overly sweet things. I still liked the idea of this recipe, so I tried to make with slight adjustments. I used 1 1/2 cups coconut sugar instead of 2 cups regular and made less peanut butter swirl. I completely omitted the peanut butter cups. They still would have been DELICIOUS if I had halved the salt and baked in a smaller pan. As is, they’re slightly overcooked and very salty. My son and hubby still like them, but if I make them again I will adjust accordingly. Thanks for the recipe.

  18. This is irresistibly delicious. Perfect consistency. Thanks, Sally!

  19. Hi Sally, huge fan of yours from England here. Just curious, for what reason do you create the peanut mixture with butter and icing sugar as opposed to using the peanut butter directly swirled on? Does it cook differently/texture come out differently? Curious to know the difference 😀 Thanks

    1. Hi Emma! With these additions, the peanut butter swirl becomes more of a delicious batter that stays intact as the brownies bake. Using just peanut butter is fine, but it isn’t as thick and will thin out as it warms and bakes.

  20. The peanut butter swirl separates these brownies and they crumble. I’m bummed! I wanted my pics to look like yours so badly. Hopefully they will taste better than they look.

    1. Hi Christine! The peanut butter layer will separate and crumble if the brownies are over-baked. I recommend a shorter bake time for your batch if you decide to try it again.

  21. Hi Sally! I love all your recipes and I was looking to see if you had a peanut butter and jelly brownie recipe and I could not find one. Could I make this one and top it with jam before putting it in the oven? Thanks.

    1. Hi Tiffany, I haven’t tested it but I don’t see why not. YUM!!

  22. These are incredible! Dangerous to keep around as there’s only two of us and we both love chocolate and peanut butter. Very easy recipe to make, too.

  23. Hi Sally, I’ve made these before and they were delicious! Could you substitute the peanut butter for a chocolate spread (like Nutella) and combine with the confectioners sugar? Or do you think this recipe works so well due to the consistency of the peanut butter?

    1. Stephanie @ Sally's Baking Addiction says:

      Hi Alex, We haven’t tested this recipe that way. However, you might enjoy these Nutella Swirl Brownies!

  24. Oh, my! These taste as amazing as they sound! They are the perfect combo of chocolate and peanut butter. And the bites with a piece of peanut butter cup?! Wowza!! I have to work on my swirl as they didn’t come out as pretty as yours, but I will definitely be making these again. And often!

  25. These turned out dry and crumbly for me. Will not be a repeat for sure.

  26. First attempt at these and they took FOREVER to bake. I have a very accurate oven with an internal thermometer. I started checking at 30 minutes and then had to bake for an additional 12-14 minutes to get a light crumb on the toothpick. I baked mine in a 13×9 glass dish…maybe that made a difference? I think the bake times (even though you recommend watching carefully) needs to be re calculated. Additionally I made the peanut butter batter exactly as recommended and it was much thinner than the picture you posted illustrated. My held together, but I could pour it into the pan…where it did hold together fairly well.

    1. Stephanie @ Sally's Baking Addiction says:

      Hi Bel, Thank you for trying this recipe! Glass pans can take longer to heat up so don’t be surprised if your bake time is longer. What type of peanut butter did you use? We find the best results with a creamy brand like Jif or Skippy (not natural or homemade).

  27. Soridalys Cruz Torres says:

    Hi Sally, do you have this recipe in smaller quantity? I actually would love to make these with my kids but smaller version. Thanks

    1. Feel free to halve this recipe for a 9-inch square pan. I’m unsure of the best bake time, but keep a close eye on them after about 25 minutes. To halve an egg, you can crack it in a bowl, whisk to combine the yolk and white, measure it, then use half. Should be a couple Tbsp. Hope you all enjoy!

  28. Hi! Can something be used at a substitute for the peanut butter cups?

    1. Lexi @ Sally's Baking Addiction says:

      Hi TM, you could use chocolate chips or some other type of chopped chocolate / peanut butter candies in place if needed. Or even chopped Oreos would be delicious!

  29. Full disclosure – I am just entering my third trimester and the cocktail of pregnancy hormones coursing through my veins has me, according to recent Pinterest searches, craving peanut butter and chocolate. I came across these brownies and thought they’d do the trick to soothe my raging sweet tooth. Little did I know this recipe is brownie perfection when I tried it out. Fudgy, dense, sweet, salty and everything I want in a brownie. The recipe was easy to follow and the results have me on cloud nine. I used a glass baking pan and let my brownies go about 36 minutes, but no dryness of the sort, even on the end pieces. I will be baking these rich treats again and again.

  30. These were rich and gooey goodness! I even omitted 1 cup of sugar and you couldn’t tell. Thanks for a great recipe for someone who doesn’t do cake!

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