Easy Sugar Free Keto Peanut Butter Fudge

Three squares of keto peanut butter fudge topped with sugar-free chocolate chips, stacked on a white plate beside a bowl of peanut butter.
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Introduction

Chocolate and peanut butter – a match made in heaven! If you’ve been around the block on this site, you’ve probably seen those words pop up a few times. And honestly, who can blame us?

Today, we’re all about simplicity. About 20 minutes at the stove is all the hands-on work here, followed by an hour in the freezer and at least two hours in the fridge to set firm, so start this one a few hours before you want to serve it. Most of that stove time goes into cooking heavy cream, butter and sweetener down until the mixture thickens and turns golden. The peanut butter gets whisked in after that, off the heat, while it’s still hot.

If you’ve been missing fudge since going keto, this keto peanut butter fudge is the one to try. Six ingredients, one saucepan, and no candy thermometer in sight – the freezer and fridge do the hard part while you get on with your day.

Let’s get cooking!

Key Ingredients

Heavy Whipping Cream

Heavy whipping cream is where this fudge gets both its richness and its set. It cooks down with the butter and the sweetener until the mixture thickens and turns a golden brown, and that reduction is the step that gives you a bar you can pick up rather than a spread you have to scoop. It is the part worth not rushing.

Being low in carbohydrate and high in fat is what lets it do that job in a keto recipe at all — the fat is carrying the flavor as well as the structure.

Unsalted Butter

Butter does a lot of things in this recipe:

  • It cooks down with the cream and sweetener into the thickened base that the whole recipe rests on.
  • It is most of why the set fudge is smooth rather than grainy or crumbly.

Unsalted, so the salt is yours to decide — particularly if you finish the pieces with a pinch of sea salt.

Lakanto Powdered Monk Fruit Sweetener

To give our peanut butter fudge its needed sweetness, we’ll be using Lakanto Powdered Monk Fruit Sweetener — a blend of erythritol and monk fruit extract. It measures cup-for-cup like sugar, which is what makes it straightforward to swap into a traditional fudge recipe without reworking the rest of the quantities. It is doing nearly all the sweetening here: nothing else that goes into the pot has sugar added to it, though the cream and the peanut butter each bring a little of their own naturally. The chocolate chips scattered over the top are sweetened too — with a sugar-free sweetener rather than sugar.

Use the powdered form rather than the granulated. It dissolves into the hot mixture instead of staying as fine crystals, and that is the difference between smooth fudge and gritty fudge.

Peanut Butter

To act as our fudge’s base, we’ll be using unsweetened natural peanut butter. Look for one with no added sugar and a short ingredient list — peanuts and salt is ideal — because plenty of jars labelled “natural” still include sugar or added oils. That shorter list also tends to give you a richer, more pronounced peanut flavor. Our store-bought brand of choice is Smucker’s, but you could try others. Just check the ingredient label and the nutrition facts.

Keto Peanut Butter Fudge

3 net carbs
Prep Time
5 minutes
Cook Time
15 minutes
Total Time
3 hours 20 minutes Includes 3 hours freezing and chilling
Yield
10 servings
Course
Dessert
Cuisine
American

Ingredients

Nutrition Facts

10 servings per recipe
Trans Fat 0g 0% 0g 0%
Allulose 0g 0% 0g 0%

About these numbers: We are home cooks, not certified nutritionists. Nutrition is shared as a courtesy. We pick a representative product for each ingredient, and our recipe system works out the totals from the amounts in this recipe, so please treat them as a helpful estimate rather than a guarantee. The brands you buy, any swaps you make, and how generously you portion the recipe will all move these numbers.

Directions

  1. Heat the heavy whipping cream and unsalted butter over medium-high heat.

    Stir the pot occasionally to prevent scorching.

  2. Add in the Sweetener.

    Once the butter has melted, whisk in Lakanto Powdered Monk Fruit Sweetener until it dissolves completely. Continue to stir constantly to ensure that the mixture does not burn.

  3. Add vanilla extract to the pot.

    Continue to cook the mixture down over medium heat until it thickens and begins to turn a bit light brown in color.

  5. Once the mixture begins to thicken and turn a golden-brown color, remove it from heat.

  6. While the mixture is still hot, whisk in the peanut butter.

    Continue mixing until the peanut butter fully combines with the mixture. You should end up with a smooth and creamy mixture.

  7. Prepare the setting pan.

    Line an 8 1/2 x 4 1/2-inch loaf pan with parchment paper, leaving enough overhang to lift the slab out later. Pour in the entire peanut butter mixture and spread it evenly.

    A loaf pan is what we would reach for — it gives this small batch the thickness the finished pieces have. A square baking dish works too and will give you something thinner and wider; either way you are cutting the same batch into ten.

  8. Sprinkle chocolate chips on top of the peanut butter mixture.

  10. Place the pan in the freezer.

    You can let your peanut butter fudge freeze for about an hour. Once frozen, transfer it to the chiller and refrigerate it for at least 2 hours or until it is set and firm.

  11. Serve and Plate.

    Once the keto peanut butter fudge is set and firm, remove it from the fridge. Cut it into ten pieces and serve. Store the remaining keto peanut butter fudge in an airtight container in the refrigerator or freezer. Eat your keto peanut butter fudge bars as is, or sprinkle them with a little sea salt. Enjoy!

Notes

  • Other powdered sweeteners work, but check what yours is before you measure. Swerve Confectioners is sold as a cup-for-cup replacement for powdered sugar, the same as the Lakanto this is written for. Plain erythritol and allulose are not — both are less sweet than sugar by volume — so taste the mixture and adjust before it goes into the pan. Whichever you reach for, use the powdered form: it mixes in easily and keeps the fudge from turning out grainy.
  • Chopped peanuts, melted chocolate chips or melted sugar-free dark chocolate can go into the mixture before it is poured into the lined pan. Add them by eye rather than to a quantity — anything extra changes the carb count in the panel, which is calculated for the ingredient list as written.
  • This is written for butter, and the butter is not only flavor here: it cooks down with the cream and sweetener, and that is the step that sets the fudge. Coconut oil and dairy-free butter are the usual stand-ins, but no adjusted version is given for either, and changing the fat changes the part of the recipe that does the setting. Treat it as your own experiment rather than a swap we can tell you the result of.
  • This recipe calls for refrigerating your keto peanut butter fudge for at least two hours to give it a firmer texture. Chilling it for a longer time will allow it to set and firm up some more. Alternatively, you can have a softer fudge if you leave it at room temperature.
  • Taste the mixture before it goes into the pan and add a little more powdered sweetener if you want it sweeter. Go in small additions: the sweetener is a bulk solid here, not a syrup, so it is part of what the set is made of — and it moves the sugar-alcohol line in the panel.
  • Whisking protein or collagen powder into the warm mixture is an idea rather than a version of this recipe — no quantity is given for it, and these powders absorb liquid, so too much leaves the fudge dry and chalky instead of creamy. If you try it, start with a very small amount.
  • Store leftover fudge in an airtight container in the refrigerator, or in a freezer-safe container if you want to keep it longer. No keeping window is given here.

Frequently Asked Questions

Can I use a different nut butter instead of peanut butter?

This fudge is written for peanut butter, and no almond-butter or other nut-butter version is given here. Peanut butter is the base of the recipe rather than a background ingredient, so another nut butter makes it a different fudge. Treat it as an experiment rather than a straight swap.

If you try one, pick a jar with no added sugar, and remember it brings its own carbs: the Nutrition Facts panel on the recipe card is for the peanut butter version.

If the reason is a peanut allergy, almond butter isn’t automatically safe. Almond is a tree nut, and some people who are allergic to peanuts react to tree nuts as well, so that is a question for the person you’re making it for, not one this recipe can answer.

How do I make this keto peanut butter fudge recipe dairy-free?

For the heavy whipping cream, you can substitute it with coconut cream. It’s a dairy-free option that’s also vegan-friendly. It has a 1:1 ratio to heavy whipping cream, making it easier to insert into the recipe. Do note that using coconut cream may result in a different overall flavor profile, but you should still end up with a delicious keto peanut butter fudge.
You can substitute the butter with a nice vegan dairy-free butter. We like this brand and have used this in a vegan peanut butter cheesecake recipe we posted.

Can sugar-free condensed milk or cream cheese replace heavy cream?

Not as a straight swap, and no reworked version is given here. The heavy cream is what cooks down with the butter and sweetener to thicken the fudge, so replacing it changes the part of the recipe that does the setting. Sugar-free condensed milk is already sweetened and much denser, and cream cheese brings its own tang and does not reduce the same way — either one needs the rest of the quantities reworked, not just substituted. If you want a cream-cheese peanut butter sweet, that is a different recipe rather than this one with a swap — and a lovely variation to develop.

Can I use homemade peanut butter in this recipe?

Absolutely! Using your homemade peanut butter can ensure that it’s sugar-free. Just ensure that what you have is creamy peanut butter and not a coarse one. You want your keto peanut butter fudge to have a smooth and creamy texture.
To make homemade peanut butter, you’d have to roast your peanuts. Then, you’d have to process them with a food processor or blender. A coffee grinder may work too, but it won’t be as effective or efficient.
Process the peanuts until they reach a smooth and creamy consistency. Make sure to scrape down the sides of the processor or blender as needed. If you want to achieve a smoother texture, adding oil, such as coconut or peanut oil, might help you. Make sure only to add a small amount.

Can I use regular chocolate chips instead of sugar-free ones?

Regular chocolate chips have added sugar, making them unsuitable for a ketogenic diet. To ensure that this recipe stays low carb, it’s recommended that you stick with keto chocolate chips or dark chocolate. If you want peanut butter fudge to have more chocolate flavor, you can incorporate unsweetened cocoa powder into the batter. If you want it to be sweeter, add more Lakanto Monk Fruit Sweetener.

Can I add other ingredients to my keto peanut butter fudge?

Sure you can! Feel free to customize your keto peanut butter fudge. Chopped nuts, coconut flakes, or a pinch of sea salt can go into the batter for more taste, or on top of the poured fudge before it chills. Just take note of the carb content of whatever you add — the nutrition figures on this recipe cover only the ingredients listed above.

Can I use a different extract instead of vanilla extract?

Yes, you can. Almond and coconut extract both work here and will pull the flavor in a different direction. Extracts are potent, so swap in the same 1 teaspoon rather than pouring by eye, and taste the mixture before it goes into the pan. If you try one, let us know in the comments how it turned out.

Wrap Up

This is a peanut butter fudge first. The chocolate is a scattering of chips over the top rather than a layer of its own, so each of the ten pieces gets a little of both, and a pinch of sea salt on top is an option if you like salty with your sweet. Check the Nutrition Facts panel in the recipe card above for the numbers per serving, then go ahead and take a piece or two.

As we alluded to in the intro, we are no strangers to peanut butter dessert combinations. If you try this, rate the recipe and let us know your thoughts in the comments below.

This isn’t the first time we’ve used these two ingredients to make a delicious treat. If you’re as crazy about peanut butter and chocolate as we are, try our Low Carb Double Stuffed Peanut Butter Cups — rich, super creamy, and full of keto-friendly flavor.

For the salty side of the pairing, our dark chocolate sea salt peanut clusters swap the peanut butter for whole roasted peanuts and finish each one with coarse sea salt.

If you’re on Instagram, share your creation there and use the hashtag #buttertogetherkitchen. Seeing your kitchen creations and how you might have tweaked the recipe to your liking is genuinely exciting.

Happy no-baking!

Correction — October 8, 2026: The nut butter FAQ now says this fudge is written for peanut butter, and that almond butter, a tree nut, isn't automatically safe for someone with a peanut allergy.