Skinny Peanut Butter Swirl Brownies

A skinny option for peanut butter brownies. Super fudgy brownies made without white flour, butter or oil!

Skinny Peanut Butter Swirl Brownies! Gluten-free, made with whole-grain oats, no flour, no butter, no oil, and with a ton of sugar substitute suggestions! These are so fudgy, you won't miss the unhealthy ingredients!

Oh my word. Do I have a treat for you guys today.

I honestly think I am dreaming because today not only am I bringing you the fudgiest, richest, softest, chewiest brownie I have EVER eaten,  I am bringing you a fudgy, rich, soft, chewy, and SKINNY brownie swirled with my one true love (sorry, Kevin): peanut butter.

Skinny & brownie in the same title is a tad ironic, but I am telling you friends… you are not dreaming.

As I begin to train for the Baltimore half marathon coming up in 4 months (anyone else out there running that? let’s be friends), I knew I needed a little treat to put some pep into my running step. Preferably something tasting sinfully chocolatey and smothered in peanut butter because, well… why not.

Most brownie recipes call for loads of butter or oil, white flour, excessive amounts of sugar, and 3+ eggs. Hence, their wonderfully decadent + rich taste. These skinny brownies, however, combine much healthier alternatives, making these brownies good enough to call breakfast. Instead of clogging the brownies with butter and oil, which would inevitably slow me down and have me feeling lethargic, I loaded the brownie batter with low fat vanilla greek yogurt. It gives these brownies that unbelievable moist and fudgy taste that I love in my favorite not-so-healthy chocolate brownies.

In fact, these brownies are so rich and fudgy that someone even told me they tasted like straight up chocolate/peanut butter FUDGE! I can’t even believe there is no oil, butter, or flour these.

Skinny Peanut Butter Swirl Brownies! Gluten-free, made with whole-grain oats, no flour, no butter, no oil, and with a ton of sugar substitute suggestions! These are so fudgy, you won't miss the unhealthy ingredients!

In addition to the low fat greek yogurt, I used fiber-rich, whole grain oats instead of white flour – whole grain carbs are a perfect way to start your day and/or fuel a workout! The recipe only calls for 1/2 cup of oats which are ground up into a flour. A brownie’s fudginess directly relates to the amount of flour in the recipe. And with only 1/2 cup of ground up oats in the entire recipe, you can imagine the density and fudginess of these babies!

My recipe has white sugar, but you could easily use 1/2 cup of honey instead. Some readers have even used Truvia, a mix of 1/2 cup brown sugar and 1/4 cup honey, or even 1/2 cup sugar and 1/2 cup dates instead of the 1 cup of white sugar. I’ve used coconut sugar instead which works wonderfully too. No matter how you chose to sweeten it, taste the batter to make sure it is sweet enough.

And to put these brownies completely over the top, I threw in a THICK peanut butter swirl because I firmly believe that there is nothing better in this world than chocolate and peanut butter. Peanut butter is full of healthy fats and protein… perfect for shiny hair, glowing skin, and keeps your muscles workin’!

You will not believe these fudgy peanut butter swirl brownies are lightened-up! Learn how to make them at

So today, here is your recipe for what may the BEST brownie you’ll ever taste. AND a brownie you can actually feel good about eating!

See more of my healthy recipes.


Skinny Peanut Butter Swirl Brownies

  • Author: Sally
  • Prep Time: 10 minutes
  • Total Time: 3 hours, 10 minutes
  • Yield: 12-16 brownies
  • Category: Brownies
  • Method: Baking
  • Cuisine: American


A skinny option for peanut butter brownies. Super fudgy brownies made without white flour, butter or oil!


  • 3/4 cup (185g) creamy peanut butter*
  • 6 ounces low fat or fat free plain or vanilla Greek yogurt
  • 1/4 cup (60ml) milk (I like to use unsweetened almond milk)
  • 1 large egg (or 2 egg whites)
  • 1/4 teaspoon salt
  • 1 teaspoon baking powder
  • 1 cup (200g) granulated sugar or coconut sugar (see note above in post about substitutions)
  • 1/2 cup (42g) unsweetened natural or dutch process cocoa powder
  • 1/2 cup (40g) old-fashioned rolled oats*


  1. Preheat oven to 350°F (177°C). Spray a 8×8 inch pan with non-stick cooking spray. Set aside.
  2. Place all of the ingredients except for the peanut butter into a blender or food processor. (Yes, a blender!) For easier blending, place the liquid ingredients into the blender first. Blend until mix is smooth and oats are ground up. You will have to stop the blender and scrape down the sides a few times.
  3. Pour batter into prepared baking dish. Batter will be thin. Microwave peanut butter for about 30 seconds. Drop melted peanut butter by spoonfuls onto the batter, swirling gently with a knife to create a marbled effect. (Try not to overmix!)
  4. Bake for 20-25 minutes or until brownies begin to pull away from the sides of the pan. Brownies will be extra fudgy, so be sure to wait until COMPLETELY cooled – I stuck mine in the refrigerator for 2 hours, which allowed them to be cut very easily. Cut into squares and enjoy!


  1. Make Ahead & Freezing Instructions: Brownies stay fresh at room temperature for 2 days, and then can be stored in the refrigerator for up to 5 days after that. Brownies freeze well up to 2-3 months.
  2. Peanut Butter: Do not use natural, runny peanut butter or powdered “peanut butter”
  3. Oats: Make sure oats are certified gluten free if gluten intolerant.
  4. Nutrition: Curious about the nutrition facts? Visit a calorie counting website with your specific ingredients/brands to determine!
  5. Adapted from Dashing Dish.


  1. Wow, yes, Peanut Butter and Chocolate is the ultimate flavor combination! I can’t wait to give these a try, love that you used the pats instead of the flour, and using a blender? Who would have thought? Good luck in the marathon, I’ll virtually train with you everyday as I walk (can’t run, bad knees.)

    1. Yes, a blender! So crazy, right? It absolutely did the trick, though. I wish we could train together! I need some blogging training buddies. Thanks Joan. 🙂

  2. Ok, so HOW do you not eat the whole pan when you bake?

    I mean wow – these are different than brownies for sure, but SO good. I used Reese PB cup chips instead of PB (only had the natural stuff around, and wasn’t sure how that would work) and they were amaaazing. A little gooey for sure, but still tasty.

    And btw the way, I was never a baker before my friend sent me the link to your blog – but I’m officially addicted now!


    1. Kerri, this comment absolutely made my day. Hearing that you now love to bake after reading my blog – how cool is that?! Thank you so much for the comment and reese pb chips in these brownies sounds amazing!

  3. these look soooo good + i can’t believe that they’re skinnyfied – how awesome is that?! must try these soon!

  4. Sara, I would suggest 35-40 minutes. Then, make sure you refridgerate the baked brownies for 2+ hours so they can set. OR I would bake them in 2 8×8 pans.

  5. Another wonderful looking peanut butter recipe. I love peanut butter and am always looking for new recipes to try. Thanks for sharing on Creative Thursday.

  6. I made these this morning and just tried them for dinner dessert! WOW! These are fabulous! I’m not even done with this batch and I already can’t wait to make them again!

  7. Those look amazing!!! Love the ingredients-they sure don’t look healthy! : )
    Can’t wait to give them a shot!

  8. Has anyone tried making these with the Walden Farms brand no calories PB spread? That and splenda and these could be totally guilt free!!

    1. I’ve never heard of that! I like regular peanut butter but let me know how you like these brownies with calorie-free peanut butter spread!

  9. These sound absolutely perfect! I am training a half-marathon in Columbus, Ohio this fall, and peanut butter and oats are two of my staples. Can’t wait to try this recipe!

    1. We have a lot in common Emily! My training eats include a lot of oats and peanut butter too – so much tasty energy!

  10. I am a HUGE fan of the peanut butter/chocolate combo. It’s comforting really, you know just know it is always going to work. However, I am a BIG fan of natural peanut butter. The kind where it’s so oily you have to use like three spoons to mix it all together. That kind. So I had a feeling that probably would not have been the best option for this recipe, so I used my newest obsession, Cookie Butter, instead. Oh my stars was it a good decision! It was like eating a cookie and a fudgy brownie together! Unbelievable. Probably not as healthy, but just as tasty 😉

    1. OH MY GOODNESS!! cookie butter swirled brownies? Now you’re talkin! I have got to try that! I can’t even imagine how tasty that would be. Thanks Olivia!

  11. I just made these and they taste great! However, when I baked them, little bubbles were coming up through the peanut butter. I was hoping when they cooled the bubbles would go away, but they didn’t. (Any idea why this could be? I used Jif Natural Creamy Peanut Butter, but I don’t think this would have made a difference. Possibly a little too much baking powder?) So mine don’t look as good as yours, but they taste fabulous! Thanks for sharing!

    1. Elaine, I am not sure what the bubbles could be. I used Jif Creamy (not natural) and did not have any bubbles. Perhaps use less baking powder next time? I’m sorry but I really am at a loss with this one!

  12. Im looking at your recipes/postings and I am convinced you and I knew one another in previous life!!!

    Everything looks delish!! The combinations and flavors are exactly the type of things I daydream of lol..

    Ive been inspired to speand a few nights this week baking 🙂

    1. LOL Elisa, that is too funny. We are dessert twins I suppose! If you like PB, you definitely can feel at home on my blog. PB + Chocolate rocks my world. Thank you so much for the sweet comment. 🙂

  13. Hi Sally, What snack did you recently post saying it gave you so much energy/fuel before your run? You said you had never felt better…… I can’t remember and I want to make it 🙂 I think it was some kind of chocolate peanut butter bar??


    1. Hey Sara! I was talking about these skinny peanut butter brownies. I had one before running one time and it was the BEST fuel. The oats, yogurt, sugar, and peanut butter kept me satiated and energized throughout the entire 7 mile run. I plan to make another batch soon for my training. THANKS! 🙂

  14. I just made these and they are pure amazing!! I am stunned that there was no need for butter or flour, and it’s just so moist! My texture came out a bit more cakey than fudgey, but that’s alright, I like it like that as well! I was wondering though, next time, can I possibly reduce the amount of sugar to maybe 1/2 cup or 3/4 cup or would that affect dramatically?

    1. I’m so glad you liked these brownies! So nice to hear. They are always a hit! You may reduce the sugar amount to however much you’d like. all it will affect is the amount of sweetness in the recipe. LEss sugar will produce a more bitter fudge brownie, but it will not affect the texture much at all.

      1. Ooh thank you! I’m making another batch tonight and will reduce the sugar. These are so addictive, I literally ate half the pan and my friends were so surprised that there was no flour or butter! You should definitely make a recipe like this for cupcakes 🙂

  15. hi, if i wish to replace the vanilla yogurt with regular butter, what will be the right amount for that? and as i don’t have a blender and wish to replace the oats with regular flour, what will be the right amount for that too?


    1. Hi again Fiona – if you were to use regular flour, butter, and not use a blender then you will have regular fudgy brownies. Use my basic fudge brownie recipe in the following linked post and swirl in 3/4 cup peanut butter before baking. POST:

    1. Hi Jesse! Yes, you may use greek yogurt instead of low fat yogurt in this recipe. I would suggest using vanilla yogurt as the plain greek yogurt is too tart. I have not tried almond flour, but I assume this would work just fine.

  16. hey so I made these but the batter was suuuuuper runny, is that normal? I had to bake them for about an extra ten minutes. the only thing different i did was use greek style yogurt and turbinado sugar, would that be why? thanks:)

    1. Hi Jasmine, the batter is supposed to be runny – even using reg. yogurt and sugar. =How did they turn out? Be sure to fully chill them before cutting. Thank you!

  17. These are truly unbelievable…and so easy to make! It really is hard to believe something low cal/low fat could taste so delicious. The first time I made them they were not overly ‘fudgy’ as you described, but they were still very good. The second time round I baked them a little less and I now know how they are supposed to taste. A…M….A….Z….I….N….G!!! Less baking time made a big difference.

    My 7 yr. old goes crazy over these. I did make a few minor changes. I cut back the sugar to 3/4 c (substituted 1/2 c. with Splenda) and instead sprinkled 1/4 c milk chocolate chips on top of the PB once out of the oven. (I may add into the batter next time round). The PB left very little chocolate exposed on the top, so I actually reduced that to 1/2 c as well.

    A big tall glass of cold milk comes highly recommended with this yummy, fudgy, stick-to-the-roof-of-your-mouth chocolate goodness! Thanks for the great recipe Sally!

    1. Hi Mary!! I am SO glad to hear that! I actually just made these the other week and took new pictures of them. I can’t wait to share the new photos with my readers. Thanks so much Mary! I love these brownies too. Merry Christmas!!

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