Kirbie's Cravings

Peanut Butter Mug Cake (low-fat version)

a close-up of a spoonful of lower-fat peanut butter mug cake
I’ve had several requests lately on how to change up some of my mug cakes to make them healthier.

Since I don’t want to kill any of my readers with all these rich recipes, I thought I’d work on making some low-fat versions.
close-up photo of lower-fat peanut butter mug cake
The peanut butter mug cake I previously made is one of my favorites. While I don’t particularly love peanut butter, the properties of the peanut butter seem perfect for a mug cake. The batter is so creamy when mixing and the cake comes so soft and fluffy you wouldn’t guess that it was made in the microwave.
close-up photo of a spoonful of peanut butter cake
I worried what would happen if I tried to make a low fat version. Since there is already fat in the peanut butter, I tried to eliminate any additional fat. I used fat free milk to replace the regular milk and vegetable oil (eliminating more than 300 calories according to this calorie count website). When mixing the batter, it was harder to smooth out the flour chunks because of the lack of fat, but a little extra mixing, and using a fork to break up some flour chunks finally did the trick.

The cake still came out pretty well. Soft, fluffy. Not as rich as the regular version of course, but still tasty. If you are looking for a healthier dessert option, I recommend splitting this dessert into two. One commenter pointed out that there are still 670 calories in the giant serving, but this really is enough to serve two, so if you split it, it’s only 335 calories. You can either cook it all in one oversized mug and split in two when finished, or cook it in two separate regular sized mugs (I recommend this latter method). I personally usually split my batter into two cups. One giant serving is too much for me in one sitting anyway.
lower-fat peanut butter mug cake photo

Here are the rest of my mug cake creations:

Peanut butter mug cake (low-fat)

Servings: 2
Prep Time: 4 minutes
Cook Time: 1 minute
Total Time: 5 minutes
Course: Dessert
Cuisine: American
This easy mug cake is a lightened-up version of my peanut butter mug cake with less fat and calories. It's light and fluffy and a nice treat when you want something sweet but don't want all the calories. This recipe is enough to make two mug cakes, but I've also included the instructions for making one big one.
4 from 1 vote


  • 4 tbsp all-purpose flour
  • 4 tbsp white granulated sugar
  • 1/4 tsp baking powder
  • 1 egg
  • 3 tbsp peanut butter
  • 6 tbsp fat free milk


How to Make Two Mug Cakes

  • Combine all of the ingredients in one mug until smooth. If there are flour chunks, use a fork to break up the chunks. Pour half of the batter into a second mug. 
  • The mug cakes need to be cooked separately. Cook one mug cake for approximately one minute. If the cake is not done cook it again for another 30 seconds. Be careful not to overcook it otherwise the cake will be rubbery. Repeat with the second mug.

How to Make One Mug Cake

  • Combine all ingredients in an oversized coffee mug. Whisk well with a small whisk until smooth. If there are flour chunks, use fork to break up chunks. 
  • Microwave on high for 1 1/2 minutes and then take it out to check to see if it is done. If not, continue to microwave in thirty-second intervals. Depending on your microwave it could take up to 2 minutes. You don’t want to overcook it or it will become rubbery. 


  • The nutrition estimate is for one serving if you make two mug cakes. If you make one big mug cake you will need to double the nutrition information.


Serving: 1mug cake, Calories: 335kcal, Carbohydrates: 42g, Protein: 11g, Fat: 14g, Saturated Fat: 3g, Sodium: 161mg, Fiber: 1g, Sugar: 28g, NET CARBS: 41

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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Recipe Rating

33 comments on “Peanut Butter Mug Cake (low-fat version)”

  1. Yummy! I made this with 3 tbsp prepared PB2 instead of the peanut butter and 9 packets of splenda instead of the sugar and it was amazing! Turned out a little gooey still at 2 min but I love it that way. Thanks for the recipe! I will definitely be making this again. My dad loved it too.

  2. Kirby, I have been gaining weight on your mug cakes for years. I love you and hate you. Thank you so much for all the great recipes!

    • hehe. If you’ve been following the more recent mug cakes, I’ve managed to reduce quite a few calories. No egg, and less oil, but still tastes good!

  3. How about making egg-less mug cakes? I’m allergic to eggs and you really don’t need 1 egg: mug cake. Egg contributes nutrition, binding qualities and leavening when whipped. I usually substitute yogurt/bananas/applesauce when making conventional recipes and they usually come out OK but in such a small recipe simple changes can make a big difference. The other issue is that I use “natural” peanut butter which contains less fat so to compensate I used low fat instead of non-fat yogurt.

  4. Replace the 4 tbsp sugar with 6 packets of Splenda sweetener and you cut out a good 36 calories! And then using all natural peanut butter helps it be a little more healthy, less preservatives and fillers and it tastes better too! And you can try taking out the egg yolk to reduce calories and such as well, but you’d probably have to use 2 eggs instead of just the one.

  5. In any of the cakes you can replace the egg with some apple sauce- it’s healthier and holy crap does it make the cake moist.

    • I have found that Greek yogurt is a great replacement. With the applesauce, I always still taste the applesauce.

  6. Love Mug cakes of all types. Living alone, these are just right. Thank you for having such a very nice variety of them.

  7. These mug cakes are wonderful. Hopefully someone creates a pina colada version.

  8. I used tahini instead of PB – it was nice also!

  9. You could try this with Better ‘n Peanut Butter or PB2 for a LOT less fat oooor with low-fat natural PB for a little less fat 😉

    • I wonder how that would affect the texture/taste. I’ll have to try it sometime though I don’t usually stock either in my house.

  10. I’m eating this now and it’s so delicious! However I did not have baking powder (all expired…) so I used cream of tartare for fun. LOL. Took 5 min instead to microwave it but I’m sure that’s because I used a lower temperature; The cake’s still nice though! Thank you for my lunch! 😀

  11. I just made this. Delicious compared to other recipes! I only put 1 1/2T of sugar, 1/2 a whisked egg, and added 1/8t. of baking soda also. Took about 1 minute split in half. A TRICK FOR MIXING: Mix dry ingredients in mug first, then add milk and egg and stir til smooth. Then add peanut butter and stir well until smooth. No lumps 🙂 Thanks for this recipe.

  12. divine! homemade cakes have never been this easy. tx for the recipe.

  13. If I divide the recipe’s ingredients by four, do I also change the time it needs to be microwaved?

    • Yes! You will definitely have to reduce the cooking time. I don’t know exactly how much. I’d start with 30 seconds and see how the batter looks.

  14. I cut the recipe in half and made it in a regular mug and that was to much for me still. Instead of the using the egg i used the egg white subsitute, which would be a 1/8 cup to half the egg. It was perfect, not too sweet, and again i couldnt even eat the whole thing that way. Thanks for the recipe, definitely a keeper for those days i am straying from the diet and i need something and dont have to feel as guilty. 🙂

    • I’m glad to hear it works with egg white substitute. I’m intrigued. I will have to try that out next time. I agree, usually half is plenty for me and sometimes too much depending on what kind of day it is. So when you eat half or less than half of this, it’s not really too bad.

  15. Looks great, but that recipe is still 686 calories. Ouch.
    The problem is the amount of peanut butter and sugar.

    • The original recipe had 3 tbsp of oil. By eliminating that, according to this one website, I eliminated 361 calories. While 686 is a lot, this recipe really makes 2 servings. It makes one very big mug oversized mug cake, or two more regular sized mug cakes. I don’t ever eat an entire overisized one, so if you cut it into two, then you are at only 343 calories each. I guess you can also further reduce the calories by using splenda or some other sugar substitute. I personally don’t like the taste of sugar substitutes, but it would reduce the calorie count.

  16. I love all of these mug cakes!

    • Yay! I’m glad. Trying to create more but I always feel bad for the eggs wasted for the creations that don’t come out right.

  17. I just figured out the nutrition facts for this bad boy..all I can say is I like the way you do low fat 😀