Keto Chocolate Peanut Butter Swirl Fudge – Rich, Easy, and Low-Carb
This fudge tastes like a treat from a fancy candy shop, but it’s made with simple ingredients you probably already have. It’s creamy, rich, and deeply chocolatey with a salty-sweet peanut butter swirl that makes every bite feel special. You don’t need a candy thermometer, and there’s no baking involved.
Just melt, stir, swirl, and chill. It’s a low-carb dessert that actually satisfies, without the sugar crash.
Ingredients
Method
- Prep your pan. Line an 8x8-inch baking pan with parchment paper, leaving overhang on two sides for easy lifting. Lightly grease the parchment.
- Make the peanut butter swirl. In a small bowl, stir peanut butter with 1–2 tablespoons of powdered sweetener and 1 tablespoon of heavy cream until smooth and pourable. Set aside.
- Melt the base. In a medium saucepan over low heat, add butter and coconut oil. Once mostly melted, add chopped unsweetened chocolate. Stir gently until smooth. Keep heat low to avoid scorching.
- Whisk in dry ingredients. Remove from heat. Whisk in cocoa powder, powdered sweetener, salt, and vanilla. Add remaining heavy cream (about 2 tablespoons). Whisk until glossy and fully combined. If it thickens too much, warm it gently and whisk again.
- Taste and adjust. Sweetness can vary by sweetener brand. Taste a small bit and add more powdered sweetener if needed. For a deeper chocolate note, stir in a pinch of espresso powder.
- Pour and swirl. Pour the chocolate mixture into the prepared pan and smooth the top. Spoon dollops of the peanut butter mixture over the surface. Use a skewer or knife to drag through the dollops, creating swirls. Don’t overwork it—2–3 passes are enough.
- Add texture (optional). Sprinkle chopped roasted peanuts or a pinch of flaky salt on top for crunch and contrast.
- Chill to set. Refrigerate for 2–3 hours, or until firm. For faster setting, freeze for 45–60 minutes.
- Slice cleanly. Lift the fudge out using the parchment. Warm a sharp knife under hot water, wipe dry, and cut into 25 small squares (5x5 grid) or 16 larger squares.
- Serve. Keep chilled until serving for the best texture. The fudge softens slightly at room temperature, which makes it extra creamy.
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Why This Recipe Works
This recipe uses a mix of unsweetened chocolate and cocoa powder for a deep chocolate flavor that doesn’t rely on sugar. The fat from butter and coconut oil adds a silky texture and helps the fudge set without crystallizing.
Peanut butter brings natural richness and that nostalgic flavor we all love. A powdered, erythritol-based sweetener keeps it smooth and keto-friendly. A pinch of salt and vanilla round everything out so it tastes like real fudge—not a compromise.
Shopping List
- Unsweetened baking chocolate (4 oz), chopped
- Unsalted butter (6 tbsp)
- Refined coconut oil (2 tbsp) – refined keeps coconut flavor mild
- Unsweetened cocoa powder (2 tbsp)
- Powdered keto sweetener (2/3 to 3/4 cup), erythritol/monk fruit blend works well
- Creamy natural peanut butter (1/3 cup), no added sugar
- Heavy cream (3 tbsp) or full-fat coconut milk for dairy-free
- Vanilla extract (1 tsp)
- Fine sea salt (1/4 tsp), plus flaky salt for topping (optional)
- Optional add-ins: chopped roasted peanuts (2–3 tbsp), espresso powder (1/2 tsp), cinnamon (1/4 tsp)
How to Make It
- Prep your pan. Line an 8×8-inch baking pan with parchment paper, leaving overhang on two sides for easy lifting.
Lightly grease the parchment.
- Make the peanut butter swirl. In a small bowl, stir peanut butter with 1–2 tablespoons of powdered sweetener and 1 tablespoon of heavy cream until smooth and pourable. Set aside.
- Melt the base. In a medium saucepan over low heat, add butter and coconut oil. Once mostly melted, add chopped unsweetened chocolate.
Stir gently until smooth. Keep heat low to avoid scorching.
- Whisk in dry ingredients. Remove from heat. Whisk in cocoa powder, powdered sweetener, salt, and vanilla.
Add remaining heavy cream (about 2 tablespoons). Whisk until glossy and fully combined. If it thickens too much, warm it gently and whisk again.
- Taste and adjust. Sweetness can vary by sweetener brand.
Taste a small bit and add more powdered sweetener if needed. For a deeper chocolate note, stir in a pinch of espresso powder.
- Pour and swirl. Pour the chocolate mixture into the prepared pan and smooth the top. Spoon dollops of the peanut butter mixture over the surface.
Use a skewer or knife to drag through the dollops, creating swirls. Don’t overwork it—2–3 passes are enough.
- Add texture (optional). Sprinkle chopped roasted peanuts or a pinch of flaky salt on top for crunch and contrast.
- Chill to set. Refrigerate for 2–3 hours, or until firm. For faster setting, freeze for 45–60 minutes.
- Slice cleanly. Lift the fudge out using the parchment.
Warm a sharp knife under hot water, wipe dry, and cut into 25 small squares (5×5 grid) or 16 larger squares.
- Serve. Keep chilled until serving for the best texture. The fudge softens slightly at room temperature, which makes it extra creamy.
Keeping It Fresh
Store the fudge in an airtight container in the fridge for up to 10 days. Separate layers with parchment to avoid sticking.
For longer storage, freeze for up to 2 months and thaw pieces in the fridge. If you prefer a firmer bite, serve straight from the freezer. If you like it creamier, let it sit out for 5–10 minutes before eating.
Why This is Good for You
- Low in carbs: Uses keto-friendly sweeteners and no added sugar, keeping net carbs low.
- Healthy fats: Butter, coconut oil, and peanut butter provide fats that help with satiety and steady energy.
- Cocoa benefits: Unsweetened cocoa and chocolate bring flavonoids and antioxidants.
- Customizable: You can adjust sweetness, salt, and add nuts to align with your goals and preferences.
What Not to Do
- Don’t boil the chocolate. High heat can seize chocolate and create a gritty texture.
- Don’t use granulated sweetener as-is. It won’t dissolve well and can make the fudge sandy.
Use powdered.
- Don’t skip the salt. A small amount sharpens flavor and balances sweetness.
- Don’t over-swirl. Too much swirling turns the peanut butter into a muddy mix instead of defined ribbons.
- Don’t choose runny peanut butter without thickening. If your peanut butter is very drippy, mix in a little extra powdered sweetener or a teaspoon of coconut flour to help it hold swirls.
Alternatives
- Nut-free: Swap peanut butter for sunflower seed butter and top with toasted pumpkin seeds.
- Dairy-free: Use coconut oil in place of butter and full-fat coconut milk instead of cream. Add a pinch of extra salt to balance the coconut.
- Almond twist: Use almond butter and add 1/4 teaspoon almond extract for a bakery-style flavor.
- Sweetener options: Allulose and monk fruit blends can make a softer, chewier fudge. Erythritol blends yield a firmer set.
Adjust to taste.
- Extra dark: Increase unsweetened cocoa to 3 tablespoons and add 1 more tablespoon cream to keep it smooth.
- Crunch lovers: Fold in 2–3 tablespoons chopped toasted nuts before pouring into the pan.
FAQ
How many carbs are in a piece?
Exact carbs depend on your ingredients and serving size, but most versions land around 2–3 net carbs per small square when cut into 25 pieces. Always calculate using your specific brands for accuracy.
Can I use milk chocolate instead?
Regular milk chocolate contains sugar and will not be keto-friendly. If you want a sweeter taste, add a bit more powdered keto sweetener to the unsweetened chocolate base or use a sugar-free dark chocolate bar.
Why is my fudge grainy?
Graininess often comes from granulated sweetener or overheated chocolate.
Use a powdered sweetener and melt over low heat. If it’s already grainy, whisk in 1–2 teaspoons warm cream to help smooth it out.
Do I have to use coconut oil?
No. You can replace coconut oil with more butter.
Coconut oil helps it firm up nicely in the fridge, but butter alone will still work with a slightly softer texture.
Can I make this without dairy?
Yes. Use coconut oil instead of butter and full-fat coconut milk in place of heavy cream. The flavor will have a light coconut note but stays delicious and rich.
How long does it take to set?
In the fridge, plan for 2–3 hours.
In the freezer, about 45–60 minutes. Setting time can vary based on thickness and your fridge temp.
What size pan should I use?
An 8×8-inch pan gives a good thickness. A 9×5-inch loaf pan also works for thicker pieces; just slice smaller squares.
Can I add protein powder?
Yes, but use a small amount so it doesn’t dry out the fudge.
Start with 1–2 tablespoons of a chocolate or unflavored low-carb protein and add an extra splash of cream to keep it smooth.
Wrapping Up
This Keto Chocolate Peanut Butter Swirl Fudge is simple, reliable, and seriously satisfying. It gives you that classic fudge experience with clean ingredients and no sugar crash. Keep a stash in the fridge for a quick dessert, a coffee companion, or a shareable treat that everyone will love—even the non-keto crowd.
Once you make it, it’ll become a go-to recipe in your rotation.
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