Mega Peanut Butter Swirl Brownies

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Incredibly moist, rich, and thick peanut butter swirl brownies! Homemade brownies with a decadent peanut butter swirl! Recipe on sallysbakingaddiction.com

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.

Incredibly moist, rich, and thick peanut butter swirl brownies! Homemade brownies with a decadent peanut butter swirl! Recipe on sallysbakingaddiction.com

But, sorry Monday, 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…

Peanut butter swirl brownies on sallysbakingaddiction.com

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. 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 for peanut butter swirl brownies on sallysbakingaddiction.com

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:

Peanut butter swirl brownies on sallysbakingaddiction.com

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 swirl brownies on sallysbakingaddiction.com

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!

Guaranteed to be the best peanut butter swirl brownies you try! Moist, fudgy, rich, and decadent brownie recipe on sallysbakingaddiction.com

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!

Incredibly moist, rich, and thick peanut butter swirl brownies! Homemade brownies with a decadent peanut butter swirl! Recipe on sallysbakingaddiction.com

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

Mega Peanut Butter Swirl Brownies

Ingredients:

  • 1 cup (16 Tbsp; 2 sticks; 230g) unsalted butter, divided
  • one 4 ounce (113g) semi-sweet chocolate bar, coarsely chopped1
  • 2 cups (400g) granulated sugar
  • 3 large eggs, at room temperature
  • 2 teaspoons pure vanilla extract, divided
  • 1 cup (95g) unsweetened natural or dutch-process cocoa powder2
  • 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 butter3
  • 1/2 cup (60g) confectioners' sugar

Directions:

  1. Preheat the oven to 350°F (177°C) and grease a 9x13 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.

Make ahead tip: Brownies freeze well up to 3 months. Thaw overnight in the refrigerator then bring to room temperature before serving.

Recipe Notes:

  1. Chocolate bars are typically sold in 4 ounce bars. I suggest Ghirardelli, Baker's brand, or Lindt. Do not use chocolate chips.
  2. You can use either natural or dutch-process cocoa powder. I prefer dutch-process for a smoother flavor.
  3. 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.

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© Sally’s Baking Addiction. All images & content are copyright protected. Please do not use my images without prior permission. If you want to republish this recipe, please re-write the recipe in your own words, or link back to this post for the recipe. Some of the links above are affiliate links, which pay me a small commission for my referral at no extra cost to you! Thank you for supporting Sally’s Baking Addiction.

Here’s that older recipe for the skinny version!

Guaranteed to be the best peanut butter swirl brownies you try! Moist, fudgy, rich, and decadent brownie recipe on sallysbakingaddiction.com
Guaranteed to be the best peanut butter swirl brownies you try! Moist, fudgy, rich, and decadent brownie recipe on sallysbakingaddiction.com

82 Comments

All Comments

  1. 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!!!!!!!!!

  2. HI Sally.
    I’ve tried to send you the Chocolate Drop Cookie recipe twice and it won’t deliver!  Arg!  Perhaps I am sending it incorrectly.  Any help?  

  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. 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!  

  5. 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!  

    1. Thank you so much, Donna! I really appreciate you coming back to let me know how much you loved the brownies. 🙂

  6. 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. 🙂

  7. 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.

  8. 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.

  9. 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.

  10. This recipe looks amazing. Is it possible to 1/2 the recipe and bake it in an 8×8 pan? Everything is easy to half but the 3 eggs. Thank you.

  11. Loved these, and so did my family. However, I can’t master the swirl to save my life. I tried it on this and on your pumpkin cheesecake bars (also delicious!) and it was an insane hot mess both times. Would you consider a video tutorial on swirling for the blockheads among us who Just. Don’t. Get. It?

  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.

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Reviews

Questions

  1. 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.

  2. This recipe looks amazing. Is it possible to 1/2 the recipe and bake it in an 8×8 pan? Everything is easy to half but the 3 eggs. Thank you.

  3. Loved these, and so did my family. However, I can’t master the swirl to save my life. I tried it on this and on your pumpkin cheesecake bars (also delicious!) and it was an insane hot mess both times. Would you consider a video tutorial on swirling for the blockheads among us who Just. Don’t. Get. It?

  4. 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.

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