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. Hi, Sally! I made these last night, being very careful to stick to the exact measurements, and they came out wet. Not wet like seeping raw goo, but wet like a very dense wet sponge, almost. I even cooked them for 27 minutes, which is very unusual for me, as I almost always have to cut my bake-times shorter than the recipe calls for.

    Do you have any ideas as to why this may have happened? Or is this just what these brownies are supposed to be like? I mean, I don’t find them particularly delicious as they turned out, but I’m also not accustomed to diet foods, so maybe this kind of thing is normal for a diet brownie. *shrugs*

    1. Hi Gabe. I apologize for the delay responding. I was on vacation. How about you grind up the oats to make a flour and then add it to the blender as noted in the recipe? I fear your oats may not be soaking up enough moisture. Also, try adding 1 more Tablespoon of oats (to make the oat flour) as well – this should help!

  2. I can’t wait to try these as I have been doing the Wheat Belly Diet for 2 months now and loving it. My question is, can i use Coconut Flour or Almond Flour in place of the oats?

  3. Hi Sally, can I substitute Kiefer for the yogurt or will it change the consistency? Its all that’s in the fridge. Thank you and love your blog!

  4. Hi Sally

    This blog is amazing for me!.
    I am 23 years old and I only recently started getting into heavy cooking and specifically baking. PS. I found great passion in it!

    As a 23 year old, I am not the richest of people (yet) – thus your Peanut Butter Swirl Brownies (I am a peanut butter freak) were affordable and easy for this beginner!
    Most of the ingredients were either in my kitchen and the adjacent very cheap in the store!

    I would love to test many of your other recipes. but sometimes I cant afford all of them, I would love to be guided to your “young and poor” aimed recipes! Or maybe even create a section for the student-type?

    Thank you so much for this recipe so far. I have changed peanut-butter lovers lives (haha!)

  5. Hey Sally these look great! A lot of my friends have peanut allergies…can I sub in almond or hazelnut butter? And for flour, are there other gluten free flours that can be used such as almond flour maybe? Can’t wait to try.

  6. Hey Sally! These look absolutely HEAVENLY and my boyfriend is a total chocolate peanut butter lover, I can’t wait to make these for him and the kids! I am actually thinking about making these TONIGHT and was wondering if I could sub the cocoa powder with melted semi-sweet chocolate chips instead…?

  7. So yummy! I didn’t have vanilla flavored yogurt, I only had plain, so I used that and added a teaspoon of vanilla extract. They came out moist and chocolatey and wonderful! I will definitely be making them again, but next time I think I’ll cut down on the peanut butter, maybe to a half cup.

  8. I can’t wait to try these! Could you tell me how many calories are in each brownie, and also what the weight in grams of the yogurt is please?
    I’m from the UK so super excited that you have your recipes in grams as well as cups so I can make them!!
    Kelly x

  9. oh my!! I have just made these and they are immense!! How are these skinny.. That are so delicious! Thankyou for sharing your recipe xx

  10. Hi Sally! I was wondering whether to use bake or fan bake for these. These look awesome though! Can’t wait!

  11. I made these tonight and they’re so delicious and fudgy! Your recipes never fail me. I did actually use natural runny peanut butter and it worked just fine and looked exactly like your photos. Also I used steel-cut oats that I ground in my food processor. In case that helps anyone!

  12. I don’t know what I did wrong, but these turned out AWFUL!  They didn’t rise one bit (only a few mm’s thick) and tasted really odd.  I did use Truvia, but can’t see that it would make that much difference?

  13. Hi Sally,this is my first comment, I wanna try these, they sound great. I was wondering if I use all natural peanut butter and put some honey in it to sweeten it, or even truvia. I know you said not to use natural, I have so many jars of the Teddie, super chunk, all natural no salt added. I eat this peanut butter, so I would love to make it work for this recipe. I’m sure other people use a no salt peanut butter also, so I’m gonna try it and let you guys know how it came out K? Wish me luck, Thanks.

  14. These were amazing!!! I am recently gluten free but I am a sucker for baking and was so excited to find this recipe. I cannot wait to try out more of yours in the future 🙂

  15. Unfortunately these didn’t work out for me at all. They turned out super super gooey so I cooked them for longer and they were still so gooey. So I stuck them in the fridge like you said and even when I took them out they weren’t fudgy at all! I don’t know what went wrong. 🙁

  16. I made these tonight and they turned out great! For the 1 cup of sugar, I used the following: 1/4 cup honey, 1/4 cup light agave syrup and 1/2 cup coconut sugar.

    I used cacao powder instead of cocoa powder AND I also through in 1 scoop of chocolate protein powder. The batter was really runny so I through it in the fridge for an hour before baking. They stayed in the oven for about 30 minutes and turned out more cakey than fudgy, which is how I like my brownies!
    Thanks for the recipe!

  17. WOW! I made these last night and although I love LOVE peanut butter, I had to leave it out as the rest of my fam aren’t fans…BUT, everyone chose their fav Halloween candy & we carefully arranged them separately  in the pan. I chose PB Cups, of course!
    Because I wanted to eat them right away I added an extra handful of oats to help solidify the brownies. I also used 3/4 C maple syrup instead of sugar. 
    We were able to eat these directly out of the even with a dalop of ice cream & we regurgitated the rest….which is where where the WOW factor comes in.
    I decided to try one this morning just because and OMG! These are like a deep dark fudge dream! It almost tastes like there’s coffee in here  🙂 I also used a high quality chocolate powder. 
    I am keeping this recipe for eva!! 

  18. Looking forward to adding these to my list of get-healthy-again recipes for January! They look so fudgy!

  19. I just had to chime in here that these brownies are also fabulous when you add a scoop of vanilla protein powder to the brownie batter! I wanted to try it because I’m pregnant and my doctor told me to have more protein snacks during the day to keep my blood sugar stable. Naturally I’m looking for snacks that involve chocolate. And peanut butter. I used a combination of agave and stevia for the sugar, and vanilla whey protein powder. They’re not quite as fudgey-gooey as when I’d previously made them without the protein powder, but they do hold up better in a lunch bag, and they still taste fudgey and delicious. My baby thanks you. 🙂

  20. Hi Sally. I made these last night and doubled the recipe. I used a 9×13 pan and baked for 26 minutes. They taste good but so moist I’m wondering if they are actually fully cooked. Since they are so fudgy, how can I tell?

  21. I’m wondering about a non-dairy sub for the yogurt. Do you have a suggestion? Applesauce? Black beans? Coconut oil? More egg? Not sure what is needed instead.

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I’m Sally, a cookbook author, photographer, and blogger. My goal is to give you the confidence and knowledge to cook and bake from scratch while providing quality recipes and plenty of pictures. Grab a cookie, take a seat, and have fun exploring! more about Sally