Kirbie's Cravings

Flourless Peanut Butter Mug Cake

This single serving microwave flourless peanut butter cake comes out light and fluffy. You won’t miss the flour at all!
photo of flourless peanut butter mug cake

I had the biggest craving for a peanut butter flavored dessert today, so I whipped this up. The recipe is just 4 simple ingredients that you likely have in your kitchen and the cake stays moist for hours so you can enjoy it right away or later on too.
overhead photo of flourless peanut butter mug cake
Do you have a recurring nightmare that you’re still in school and suddenly it’s finals and you’re completely unprepared? Even though I’ve been out of school for a decade, I still periodically have that nightmare. I wonder when, or if ever, it will go away.

I recently have been having a similar series of panic moments over my upcoming book. It’s been a few months now since I turned in the final draft, and every once in a while, I’ll find myself freaking out because I think I messed up one of the recipes even though I tested and retested all the recipes over and over again before turning in the book. That’s what happened when I made this mug cake. I looked up the recipe and noticed that the original recipe I posted two years ago and the one in the book are different.

photo of a spoon dipping into a flourless peanut butter mug cake

So I started panicking, but luckily, it was all for nothing. The recipe does work as written (just like all the other ones I recently freaked out over). It is one of the ones I tinkered and improved upon for the upcoming book.

I really enjoy how easy this recipe is. It expands quite a bit in the microwave before deflating a little after it has cooled. It has a sweet, pleasant peanut butter flavor. It also continues to stay moist for hours and the peanut butter flavor actually becomes more prominent if you let it sit for a few hours, though it tastes great straight from the microwave too.

flourless peanut butter mug cake in a blue mug

You can check out my whole collection of mug cake recipes here.

As mentioned above, this recipe is featured in my new cookbook of nearly 100  mug cakes!


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Update! This recipe is now updated with video.

Flourless Peanut Butter Mug Cake

Servings: 1
Prep Time: 4 minutes
Cook Time: 1 minute
Total Time: 5 minutes
Course: Dessert
Cuisine: American
A single serving flourless peanut butter mug cake that cooks in the microwave!
5 from 2 votes


  • 2 tbsp peanut butter creamy
  • 1/8 tsp baking powder
  • 1 tbsp white granulated sugar
  • 1 large egg


  • Whisk all ingredients into an oversized, microwave-safe mug until batter is smooth. Microwave for about 1 minute. Let cake cool a few minutes before eating.



Serving: 1mug cake, Calories: 312kcal, Carbohydrates: 20.3g, Protein: 13.4g, Fat: 21.2g, Saturated Fat: 4.9g, Sodium: 208mg, Fiber: 1.6g, Sugar: 16g, NET CARBS: 19g

The nutrition information provided are only estimates based on an online nutritional calculator. I am not a certified nutritionist. Please consult a professional nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.

Did you make this recipe?I'd love to see it! Mention @KirbieCravings and tag #kirbiecravings!

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100 comments on “Flourless Peanut Butter Mug Cake”

  1. this is the easiest mug cake ever and it was so good only 3 ingredients. very moist, very spongy. the only thing that i recommend is putting on top a few chocolate chips or what i do is make a very simple frosting and all it is, is 2 tablespoons of unsweetened cocoa powder and 2 tablespoons of powdered sugar and mix and the add a teaspoon of milk at a time until you like the consistency and usually i like it to be very runny so i add a tablespoon of milk. but anyways this is my favorite mug cake ever. oh and i don’t make it in a mug i make it in a bowl because it makes it easier to clean after. ??

  2. Cake for breakfast?! I think so. I subbed monk fruit sweetener blend for the sugar. Loved it! So quick and easy. Used my pampered chef ceramic egg cooker without the lid in place of a mug. 

  3. I followed the written recipe, adding some chocolate chips and it was PERFECT! I did notice that your video shows to use baking soda and the written recipe says to use baking powder, I used baking powder for perfect results. That might be why some people commented that they got different results.

  4. Thank you so much Kirbie!
    I love cake, my husband isn’t a fan tho so I don’t often bake myself unless we are having visitors. Today I had a craving for cake and I remembered mug cakes from years ago and started looking for a recipe. Luckily for me I found your website and while looking around I found your 2 flourless peanut butter mug cakes and thought I had to give 1 a try.
    I must admit I couldn’t quite get my head around a flourless cake ahead of making it myself.. I ad libbed a bit as I think my eggs aren’t quite as large as they should be and the consistency wasn’t the same as in your video.
    Wow!! I couldn’t believe it when it came out so well! This was perfect!!
    I am definitely going to try more of your recipes 🙂

  5. This was amazing! This is the best mug cake I have ever had. Thank you for posting!

  6. I just made this with no-sugar added peanut butter, and replaced the sugar with Swerve for a low-carb/keto version. It was excellent!

  7. Can you do the same with almond butter. Allergic to peanuts

  8. So yummy! Just enough of a peanut buttery treat 🙂

  9. Does anyone know how many carbs are in this cake?

    • I do not have that information but caloriecount and myfitnesspal are both great resources for calculating nutritional value for recipes

  10. I made this twice. The first time, I used Truvia and it was a complete disaster. The second time, I followed the directions EXACTLY and it was a perfect moist peanut butter cake. The taste and texture were both perfect. 

  11. Really want to try this but can you use caster sugar instead of granulated sugar?

  12. I LOVE it….I used splendor instead of sugar and it came out fine. Very yummy. Thanks for posting..I love mug cakes. Where can I get your cookbook?

  13. Delicious! I put peanut butter on top at the end so it would melt and I also put Hershey’s chocolate syrup so I could have a chocolate-peanut butter combo. 

  14. Love it????

  15. this was my first mug cake and it was yummy cant wait to try different combinations 

  16. Made this for the first time last night!  Boy was I surprised. Today I made one using Nutella!  Wonderful!!  Tasted like a brownie!  Think I’ll chop up some walnuts in my next cake!

  17. Best mug cake I’ve ever tried! Perfect for my low carb diet! Thank you!

  18. I just made this, I substituted 2tbls of Xytrol for the sugar (I like sweet) It worked great and wasn’t as sweet as I expected. But much more like cake then I expected, even hubby like it 🙂 Thank you for the great recipe. 

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