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. You might like my flourless peanut butter cake, too!

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


Twitter Facebook | Instagram Pinterest | Google +


RSS | Email | Bloglovin

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 3 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: 19

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!

Related Recipes

Flourless Peanut Butter Chocolate Chip Mug Cake

3 Ingredient Flourless Peanut Butter Mug Cake

3 Ingredient Flourless Nutella Mug Cake

Subscribe to receive new post updates via email

don’t miss a thing!

Get new post updates via email:

5 from 3 votes

Leave a Reply

Your email address will not be published. Required fields are marked *

Recipe Rating

102 comments on “Flourless Peanut Butter Mug Cake”

  1. Well it was pretty good I made it in a little longer than five mins but I’m a kid so it was kinda hard this tasted so good though I’m have this as a perfect review

  2. 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. ??

  3. 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. 

  4. 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.

  5. 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 🙂

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

  7. 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!

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

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

  10. 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

  11. 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. 

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

  13. 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?

  14. 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. 

  15. Love it????

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

  17. 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!

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

  19. 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. 

  20. Would Almond butter work in this recipe?

  21. I made this using Natural Peanut Butter.  I thought the Natural PB would be too dense, but it worked out okay.  Since Natural PB has no sugar in it, I think next time I will add a little more sugar.  Also, Cinnamon and PB is WONDERFUL together!!!  

    Two Tips for your readers:  if you have a kitchen scale that measures in grams, simply weigh your PB.  My package said that 2T is = 32 grams, so I put my bowl on the scale, zeroed out the scale, and scooped PB until the scale read 48 grams.  If you have to use measuring spoons, spray the spoons with Pam (or similar non-stick spray) first, then measure the PB.  It should fall right out of the spoon.  

  22. I just tried this recipe today.  It is the first time I tried a mug cake recipe.  It was absolutely delicious.  I subbed out the sugar and just used 1 packet of sweetner and I cooked mine in a bowl so I could add a scoop of double chocolate icecream.  O. M. G. !!!  While I wouldn’t say it was cake (more like a really stiff custard), it will be one of my go to sweet tooth craving late night quick snack without killing my blood sugar recipes.  Thank you!  Its hard to adjust to low carb diet since I found out I’m diabetic.  This could literally save my life!

  23. Can you do anything other than white sugar?  I don’t do white sugar or corn syrup.  Try to do no sugar other than maybe something like fruit.  I saw you mentioned dark chocolate.  Did you sweeten it with that?

  24. It works at first try. Spongy and tasty! Used chunky peanut butter, and added 1 tsp of cocoa powder and a dash of vanilla extract as recommended by some commentors. Thanks for sharing it 🙂

  25. Just made this because I wanted a little something sweet after lunch.  It was delicious and it had the perfect texture. Thanks!

  26. Has anyone tried this with an egg substitute? Like Flax seed?

  27. just made this for the first time and it is amazing 

  28. Luv luv luuuuuuv it a lot . Easy and delicious 😀

  29. I just tried this mine wasn’t as fluffy as in the picture but yummy 😕

    • you might have needed to cook it longer. if it’s not quite done enough, it will sink back down and be dense. every microwave is different. try maybe adding 15-20 seconds next time. another thing could be your baking powder. make sure it’s fresh!

  30. This recipe kind of blew my mind. I was pleasantly surprised, this was pretty good. This opens up some new possibilities. Thank you for posting.

  31. This was so amazing! I used half peanut butter half cookie butter! I made mug cake once before and it came out horrible but this was perfect! Low cal and low carb too! 😀

  32. I made a second attempt, and it turned out completely fine and delicious! I don’t know what happened the first time, but I’m glad I gave it a second chance. 

    • Yay! i’m so glad you did too. if you’re like me, it probably was just adding the wrong quantity of something without realizing it.

  33. I must have done something wrong because it came out with a bad texture and an even worse taste. Sad, because I love peanut butter 

    • hi Emily. it’s hard for me to figure out where yours went wrong without me being there watching what you did. Did you substitute any ingredients or change any of the steps?

  34. so i have been looking for the perfect mug cake and I think I have found exactly that

  35. Hello. I was wondering if this recipe would work using splenda?

  36. Soooo good!  I even tried two different versions:  nutella, and super chunky peanut butter but I am wondering if you can use egg whites instead.  

  37. How long and what temp could you do this in the oven? We don’t have a microwave. Thanks!

  38. absolutely delicious! next time I might add banana!

  39. Has anyone tried with extra peanut butter? Make it more gooey??

  40. Has anyone tried this with no sugar or sugar substitute? I’m diabetic so I’ve very conservative with sugars. Thanks!

  41. i loved how easy this was! I threw in some semi sweet chocolate chips and it came out amazing! 

  42. this looks amazing I would love to try but could anyone tell me how many calories please? 

    Thanks xx

  43. I think I did something wrong, because it just turned out to be an egg covered in peanut butter…

    • Did you thoroughly mix all the ingredients? And did you do anything else differently such as change measurements, leave anything out, cook in an oven instead of microwave?

  44. I enjoyed this!

  45. I’ve made this twice in two days! I love the simplicity of it and that the texture is like real cake. I used natural peanut butter and subbed erythritol and stevia for the sugar and it was great! I added cinnamon and vanilla extract the second time and it turned out pretty yummy. 

  46. This is so good! 
    I used a little more sugar – about 1 1/2  tblspoon – and a teaspoon of chocolate powder. It was sooo delicious!

  47. I made this tonight (First time ever making a mug cake.) OH MY GOSH it was so so yummy. I was a bit wary at first because I’ve heard about the disaster mug cakes and imagine my surprise when this cake was utterly amazing! It’s so light and fluffy. The only problem I had was it wasn’t sweet enough, but I drizzled some honey on top and that was fixed.

    • so glad you like it! I agree, it’s not overly sweet. I usually make pb desserts less sweet and more peanut buttery and I figure people can always add frosting or a drizzle of something if they want it sweeter. I hope you’ll check out my other mug cakes or my mugcake book!

  48. You had me sold at peanut butter and flourless! I’ve never tried mug cakes before, but love the easiness of it.

  49. I used some called Dark Chocolate Dreams (chocolate & peanut butter mix) and it was so good!