Keto Peanut Butter Fudge


This is the best keto peanut butter fudge you’ll ever try. It’s creamy, buttery, rich, ultra-satisfying and keto-friendly! The trifecta of a great low carb dessert. Low carb peanut butter fudge…YUM!! I was craving chocolate fudge and peanut butter, so I made this keto peanut butter fudge that turned out delicious!

Keto Peanut Butter Fudge

Ultra creamy, three-ingredient Keto Peanut Butter Fudge that is only 2 net carbs per slice!

My favorite Keto Peanut Butter Fudge has only three ingredients and takes just a few minutes to make. This ultra creamy fudge has a caramel base that adds a rich flavor you will love! Once you make the keto caramel, just stir in peanut butter, freeze and top with a little sea salt for a decadent keto holiday dessert!

The ultra low carb count makes this fudge a great keto snack. This could also be called a keto fat bomb. A ketogenic diet is a low-carb, high fat diet. When on keto your primary energy source is fat, so people often add fat bombs to their diet to meet their quota or add a little boost. Fat bombs can be sweet or savory they must be low in carbs and high in fat.

Ingredients in Keto Peanut Butter Fudge

This low carb peanut butter fudge recipe has three ingredients:  

  • butter
  • swerve brown sugar sweetener
  • peanut butter

You will find this recipe has the best flavor and results with butter and the brown sugar swerve. If you swap those for granular Swerve it will lack the same rich caramel flavor that the brown sugar version provides.

However it will still be sweet and delicious, just not quite the same. You definitely can switch the peanut butter for a different nut butter, just make sure it is a low carb/no sugar added version to keep your carbs at bay. 

Can You Have Peanut Butter on Keto? 

Yes! For this recipe, any peanut butter will work so long as it’s not one of the high-carb versions that contain extra honey or sweeteners. 

How to Make Keto Peanut Butter Fudge

This keto-friendly peanut butter fudge couldn’t be simpler to make! Here are the basic steps: 

  1. In a sauce pan, melt the butter and add brown sugar.
  2. Stir continuously until sugar dissolves and it begins to simmer and a thick brown caramel begins to form. 
  3. When the sauce is thickened and looks like caramel remove from heat and stir in the peanut butter until melted.
  4. Line a loaf pan with wax paper and carefully pour the fudge into the pan.
  5. Freeze until completely set.
  6. Peel the wax paper away from the fudge and slice. 
  7. Top with sea salt as desired.

How to Store Keto Fudge 

After slicing I find these store best in an air tight container in the freezer. Simply set them out one at a time for a few minutes to allow them to thaw. When thawed just a bit they melt in your mouth! 

Tips for Making Low-Carb Peanut Butter Fudge

  • For added flavor, add 1 teaspoon vanilla extract to the keto fudge. 
  • I like to slice the loaf of fudge into three long, skinny rows, then slice the long rows into 7 chunk-size pieces.
  • If stored in the freezer, this keto-friendly peanut butter fudge will last up to 3 months. 


You can make this rich, creamy keto peanut butter fudge using only five ingredients that most people have on hand.

This keto peanut butter fudge recipe is perfect for sharing or freezing for a later date. Dairy-free option included.


If you love peanut butter and you love treats with peanut butter, you’re going to want to make this easy keto peanut butter fudge. This low carb peanut butter fudge recipe is super simple to make.

You can add chopped nuts, sugar-free chocolate chips or a little sea salt for a fun add-in option. You can also wrap individual pieces and give them away as gifts.


  1. Add the peanut butter and butter to a medium mixing bowl. Cover the bowl and microwave for a minute at a time, until the butter is melted.
  2. Remove the bowl from the microwave and add the vanilla and salt. Stir until the mixture is well combined. Be careful, the bowl will be hot.
  3. Add the sugar-free powdered sugar and stir until completely combined.
  4. Transfer keto peanut butter fudge into your prepared pan and smooth the top.
  5. Cover and chill for at least 6 hours or overnight.
  6. To cut the peanut butter fudge, lift the parchment paper with the fudge out of the pan and place it on a cutting board before cutting into squares.

These numbered steps match the numbered photos above and are for illustration purposes only. Please see the printable recipe card below for the full set of instuctions.

How to make keto peanut butter fudge on a stove top:

In a medium sauce pan, melt sugar-free peanut butter and butter together over medium heat. Add in vanilla and salt and stir until combined.

Add in the sugar-free powdered sugar and stir until combined. Follow the remaining steps above for setting the fudge.

Can you freeze peanut butter fudge?

Yes, most fudge recipes freeze well, especially this keto peanut butter fudge recipe. You can freeze this peanut butter fudge in a sealed container for up to three months.

Can I use homemade peanut butter to make peanut butter fudge?

I don’t typically recommend homemade peanut butter when making keto peanut butter fudge as it tends to have more oil and be runnier, which makes it hard to set up properly.

If you have thick homemade peanut butter go ahead and give it a try, otherwise use store bought sugar-free peanut butter.

Dairy-free Keto Peanut Butter Fudge

Use dairy-free butter to make this keto peanut butter fudge dairy-free. We’ve used earth balance butter spread with success. I haven’t tried coconut oil in this recipe, but when I do, I’ll post about it here.

Sugar-Free Peanut Butter

Peanut butter is naturally a little sweet but most brands add sugar. You’ll want to look for a natural peanut butter that is either sugar-free or has no added sugar.

Sugar-free peanut butters sometimes add sugar alternatives. Look at labels and pick which one is best for you.


This sugar-free keto peanut butter fudge recipe is rich, fudgy, and easy to make with just 4 ingredients. Naturally gluten-free, with a dairy-free option.

If you’re a peanut butter lover like me, you have to try this sugar-free keto peanut butter fudge recipe. The taste and texture is spot on, you need just a few ingredients, and you won’t be able to tell the difference at all between this and regular old-fashioned peanut butter fudge with powdered sugar.

Nobody likes gritty fudge, so using a keto powdered sweetener is so important! This recipe relies on Besti Powdered Monk Fruit Allulose Blend because it tastes just like sugar, dissolves easily into the fudge base, and clocks in at zero grams net carbs.


  • Sweet peanut butter flavor
  • Silky smooth, fudgy texture
  • Preps in just 10 minutes
  • Only 3 grams net carbs in a large serving (or less than 1 gram for 1-inch squares!)
  • Protein-rich snack


This section explains how to choose the best ingredients for peanut butter keto fudge, what each one does in the recipe, and substitution options. For measurements, see the recipe card below.

  • Peanut Butter – Make sure it’s salted and has no added sugar (check labels!). Also, for the fudge to set, it’s important that it’s the thick, creamy kind, not the runny kind. Many brands labeled “natural peanut butter” are too runny for this recipe. I like this brand, which is thick and creamy.
  • Butter – I prefer grass fed butter for best flavor and nutrition, but you can use any unsalted butter. If you use an unsalted peanut butter, then your butter should be salted instead.
  • Besti Powdered Monk Fruit Allulose Blend – Not only does it taste and act like powdered sugar, it also dissolves easily (unlike other keto sweeteners), for a completely smooth fudge texture. If you have to replace this with a different sweetener, make sure it’s powdered, but keep in mind that powdered erythritol based sweeteners (including most other brands of stevia and monk fruit) may crystallize when storing and create a gritty texture.
  • Protein Powder – I used collagen (this brand is great!), but any neutral protein powder should work for sugar-free peanut butter fudge. Be sure it’s unsweetened.
  • Vanilla Extract – Optional, but recommended for flavor. You can also use different extracts here to change it up.


This section shows how to make sugar-free peanut butter fudge with step-by-step photos and details about the technique. For full instructions, see the recipe card below.

  • Prep the pan. Line an 8×8 pan with parchment paper or wax paper, letting the paper hang over the sides.
  • Melt peanut butter and butter. In a large mixing bowl, heat peanut butter and butter in the microwave, or in a sauce pan on the stove over low to medium heat, until melted.
  • Mix keto friendly peanut butter fudge. Stir in Besti Monk Fruit Allulose Blend and collagen powder, until smooth. Taste and adjust sweetener to taste. Remove from heat and stir in vanilla.
  • Freeze. Pour the mixture into the lined pan and freeze until firm. (You can also chill in the fridge instead, but the fudge will be more soft.)

TIP: Add toppings before chilling if you like. See variation ideas below!

  • Slice. Lift the parchment paper out of pan and place fudge onto a cutting board. Slice into squares.

TIP: A warm, wet knife slices more easily.

Run the knife under hot water before slicing, and anytime you notice sticking.


  • Double peanut – Sprinkle some chopped peanuts over the top, or fold into the batter.
  • Chocolate chip – Fold sugar-free dark chocolate chips into the batter before chilling, or simply sprinkle on top.
  • Buckeye – After making the peanut butter layer, make keto chocolate fudge and pour that over the peanut butter before chilling. (You can also make individual keto buckeyes like this instead.)
  • White chocolate – Melt 1/2 cup sugar-free white chocolate chips and stir into the fudge batter.
  • Maple walnut – Replace 2-3 tablespoons of the peanut butter with keto maple syrup. Add 2-3 more tablespoons of collagen and 1/3 cup chopped walnuts.
  • Sea salt – Sprinkle flaky sea salt over the fudge before freezing.


Traditional peanut butter fudge has about 16 grams carbs per 1-inch piece. Instead, this sugar-free peanut butter fudge recipe has just 3 grams net carbs in a 2×2-inch piece (that’s 4 times the serving size!). If you cut the fudge into 1-inch pieces, each one will have less than 1 net carb.


Store the sliced keto peanut butter fudge bars in an airtight container in the freezer. Soften on the counter for a few minutes before serving. (They are also okay in the refrigerator, but will be softer and harder to handle.)

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