Kirbie's Cravings

Keto 3 Ingredient Microwave Peanut Butter Fudge

This low carb and keto-friendly peanut butter fudge is just 3 ingredients and can be cooked in the microwave. The fudge is creamy, peanut buttery and makes a delicious snack.
photo of a stack of peanut butter fudge

After successfully making an easy 2 ingredient keto fudge, I have been determined to create an easy keto peanut butter fudge. It took me about half a dozen attempts, but I finally have a recipe I’m excited to share.

Ingredients for Keto Peanut Butter Fudge

  • creamy peanut butter
  • butter
  • powdered erythritol

Taste and Texture

This fudge has a texture similar to traditional fudge. It’s fudgy, chewy, and creamy. There is a little bit of taste and texture from the sweetener, but it can’t really be helped. If you’ve worked with powdered erythritol before, you know it doesn’t melt quite as well as regular sugar, but it still tastes and looks pretty darn close.

photo of a slices of peanut butter fudge

How to Make Keto Fudge in the Microwave

  • The peanut butter and butter are melted in the microwave and then whisked together until smooth.
  • The powdered erythritol is then whisked in.
  • The peanut butter mixture is then heated again in the microwave. This helps the powdered erythritol melt into the peanut butter.
  • The mixture is then poured into a loaf pan and placed into the freezer for about 1 hour to set.
  • Let the fudge soften slightly before slicing.

close-up photo of a slice of fudge

You might like my keto chocolate peanut butter fudge, too!

Keto 3 Ingredient Microwave Peanut Butter Fudge

Servings: 18 pieces
Prep Time: 10 minutes
Resting Time: 1 hour
Total Time: 1 hour 10 minutes
Course: Dessert
Cuisine: American
This easy peanut butter fudge is cooked in the microwave and only needs three ingredients.
5 from 5 votes


  • 4 ounces unsalted butter room temperature
  • 1/2 cup creamy unsweetened peanut butter
  • 1/2 cup powdered erythritol


  • Line an 8 x 4 inch loaf pan with parchment paper.
  • Add the butter into a large microwave-safe bowl. Add peanut butter to the bowl, covering the butter. This will prevent the butter from popping and overheating while it cooks.
  • Microwave at full power for 30 seconds. Remove and stir with a whisk. If butter is not completely melted, microwave for 30 more seconds and whisk again.
  • Add the powdered erythritol to the peanut butter mixture and stir until batter is smooth.
  • Place batter back into microwave and cook for 1 minute. Remove and whisk until smooth. This will help the sugar melt into the peanut butter mixture. Microwave for 1 more minute and whisk until smooth.
  • Spread batter into the prepared loaf pan. Freeze for about 1 hour or until fudge is cooled and set.
  • Let fudge soften for a few minutes and then cut with a sharp knife into 1 inch squares. You should have enough for 18 pieces.


  • For photo purposes, I did cut the fudge pieces a little bigger but this fudge is very rich so I usually cut into 1 inch wide squares (the fudge is about 3/4 inch thick).
  • Even if the peanut butter mixture looks smooth after whisking in the erythritol, you still want to heat it up for those extra 2 minutes (at 1 minute intervals) to help dissolve the erythritol. 
  • I use So Nourished powdered erythritol* You can also use powdered Swerve.
  • Make sure to use powdered erythritol because granular will not melt into the fudge.
  • This fudge can also be prepared on the stove in a double boiler. Just make sure to heat long enough after the sweetener is added to allow it to melt into the peanut butter mixture.
  • *Some of the product links contained in this post are affiliate links. Much like referral codes, this means I earn a small commission if you purchase a product I referred (at no extra charge to you).
  • The estimated nutrition carbohydrates count excludes sugar alcohols. The net carbs excludes both fiber and sugar alcohols.


Serving: 1piece, Calories: 90kcal, Carbohydrates: 2g, Protein: 2g, Fat: 9g, Saturated Fat: 3g, Sodium: 1mg, Fiber: 1g, Sugar: 1g, NET CARBS: 1

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

20 comments on “Keto 3 Ingredient Microwave Peanut Butter Fudge”

  1. I made this for Christmas and it git raves reviews. I keep in my freezer and snack on it when I get a craving. Super fast and easy to make and oh so good

  2. This fudge is excellent and guilt-free! Yum!

  3. I’ve made this with crunch Peanut Butter & sometimes I add mct oil, vanilla or cinnamon to it to change it up, I love it & keep it frozen in the freezer, cause I’m the only one eating it. . thanks for this delicious recipe.

  4. Tried it out…was super easy to make and delish! Thanks!

  5. Did you mean to say cut into 8 pieces? 18 seems super small. 

  6. Tried this with monk fruit sweetener and absolutely loved it! Thanks for the recipe 🙂

  7. Could a layer of chocolate be added on the top for a Reese’s affect?

  8. I made this fudge and OMG it was awesome!! So rich and peanut buttery, I love it!! Very simple to make.

  9. Do you know if I could use powdered butter as a substitution for real butter? If so details please!