Low-Carb Peanut Butter Fudge (Keto)
I make a lot of snack-y things in my kitchen, but this peanut butter fudge keeps coming back into rotation. It’s forgiving, quick to pull together, and satisfies that dense, creamy, slightly chewy bite I crave without the carbs. If you’re on keto or just cutting sugar, this is the kind of treat that feels indulgent while staying within a low-carb framework.
There’s no baking, no tempering chocolate, and no complicated technique—just gentle heat and a little patience while it sets. I like to keep the ingredients simple and straightforward so the peanut butter flavor shines. A couple of optional add-ins let you tweak texture and nutrition without messing with the basic method.
Below you’ll find exactly what I use, step-by-step directions (followed as written), equipment notes, trouble-shooting tips, and a few allergy-friendly swaps. Read straight through before you start; the recipe moves quickly once the pan is ready and the stovetop is warm.
Your Shopping Guide
Before you begin, gather everything so there’s no last-minute sprint to the pantry. Focus on quality for the main ingredient: the peanut butter. Unsweetened, creamy nut butter will give you a smooth, rich fudge base without extra sugars. Pick a sugar-free confectioners sweetener you like the taste of—different brands can affect sweetness and mouthfeel.
Ghee or coconut butter brings fat and helps the texture set cleanly. If you plan to add collagen, grab Marine Collagen or beef collagen. Vanilla and cinnamon are optional but they layer flavor; sea salt is small in quantity but important for balance. Also make sure you have a loaf pan or an 8″ x 8″ pan and parchment—the overhang makes removal simple.
Low-Carb Peanut Butter Fudge (Keto): From Prep to Plate
Ingredients
- 116-ounce jar unsweetened creamy peanut butter — the base and main flavor; creamy gives the smoothest texture.
- 2/3 cup sugar-free confectioners sweetener — sweetens without carbs; confectioners style blends smoothly into the fat.
- 1/3 cup ghee or coconut butter — adds richness and helps the fudge set; choose ghee for neutral flavor, coconut butter for a hint of coconut.
- 3 Tbsp Marine Collagen or beef collagen, optional — optional protein boost and slightly firmer texture when chilled.
- 1/8 tsp sea salt — enhances the peanut flavor; don’t skip it unless you have a sodium restriction.
- 1 tsp pure vanilla extract, optional — optional for aromatic depth; a little goes a long way.
- 1/2 tsp ground cinnamon, optional — optional for warmth and complexity; good if you like spice notes with peanut butter.
Instructions
- Line a 9″ x 5″ loaf pan or an 8″ x 8″ cake pan with parchment paper, leaving a few inches of overhang on two sides to lift the fudge out later.
- In a small saucepan, combine the following: 116-ounce jar unsweetened creamy peanut butter, 2/3 cup sugar-free confectioners sweetener, 1/3 cup ghee or coconut butter, 3 Tbsp Marine Collagen or beef collagen (optional), 1/8 tsp sea salt, 1 tsp pure vanilla extract (optional), and 1/2 tsp ground cinnamon (optional).
- Heat the saucepan over medium-low. Stir constantly until the mixture is fully melted and smooth, and all ingredients are well combined. Do not boil; remove from heat as soon as the mixture is evenly creamy.
- Pour the warm peanut butter mixture into the prepared pan and use a spatula to smooth it into an even layer.
- Place the pan in the freezer and chill for at least 2 hours, or until the fudge is firm and set.
- Remove the pan from the freezer, use the parchment overhang to lift the fudge out, and transfer it to a cutting board. If desired, let it sit at room temperature for a minute to ease cutting, then cut into squares with a sharp knife.
- Store leftovers in a zip-top bag in the freezer.
Top Reasons to Make Low-Carb Peanut Butter Fudge (Keto)
1) It’s fast. From start to chill, the active work time is under 10 minutes. The rest is hands-off chilling in the freezer.
2) It’s forgiving. The recipe is tolerant of small timing variations. As long as you don’t boil the mix, the texture will set nicely.
3) It satisfies cravings without sugar. If you’re avoiding carbs or sugar, this delivers a dense, candy-like bite that keeps you on track.
4) It’s customizable. You can tweak texture and flavor with optional collagen, vanilla, or cinnamon, and you can experiment with nut butters if you need a different allergen profile.
Ingredient Flex Options
Use these adjustments if you want to alter texture or flavor while keeping the method the same.
– For firmer fudge: keep the collagen in the mix; it helps the set and gives a slightly chewier texture. If you skip collagen, the fudge will still set thanks to the fats, but it may be a touch softer.
– For different sweetness profiles: the recipe calls for a sugar-free confectioners sweetener. Erythritol- or monk fruit–based blends both work; pick one you enjoy. Confectioners style prevents grittiness.
– For more coconut flavor: choose coconut butter instead of ghee. The coconut butter will add aroma and a little sweetness.
Equipment & Tools
Minimal gear is required. You’ll need:
- Small saucepan — for gently heating and combining the ingredients.
- Spatula or wooden spoon — for stirring and smoothing the mixture into the pan.
- 9″ x 5″ loaf pan or 8″ x 8″ cake pan — for shaping the fudge.
- Parchment paper — with overhang on two sides to lift the set fudge cleanly.
- Sharp knife and cutting board — for slicing the fudge into squares.
- Freezer space — a level surface so the fudge sets evenly.
Slip-Ups to Skip
Don’t overheat. The instructions say medium-low and to avoid boiling. High heat can separate oils and change texture.
Don’t skip the parchment overhang. Trying to pry fudge out of a pan without it usually leads to breakage.
Avoid using a gritty sweetener. The recipe specifies confectioners-style sweetener to keep the surface smooth—granular sweeteners can leave a sandy mouthfeel.
Allergy-Friendly Swaps
If peanuts are a no-go, swap in a neutral-tasting nut or seed butter with similar fat content—almond butter or sunflower seed butter work well for many people. Keep it unsweetened and creamy to match the original texture. If coconut is an issue, use ghee (if dairy is tolerated) rather than coconut butter. For those avoiding beef/marine products, simply omit the collagen; the fudge will still set.
Cook’s Notes
Texture: The fudge is rich and dense straight from the freezer. If you prefer a slightly softer bite, set it for the minimum time and let squares sit at room temperature for a couple of minutes before eating.
Cutting: Run a sharp knife under hot water, dry it, and then slice for cleaner edges. Wipe the blade between cuts if you want neat squares.
Flavor balance: A tiny pinch more sea salt can brighten the peanut flavor if you find it flat. Taste the melted mixture carefully once it’s combined and off the heat, and adjust if needed.
Save It for Later
Leftovers should be stored in a zip-top bag in the freezer, as in the instructions. Separate layers with parchment if stacking to prevent sticking. Thaw individual squares at room temperature for a few minutes before enjoying. The fudge keeps well frozen and maintains texture; for best quality, plan to eat within a few months.
Your Top Questions
Q: Can I use crunchy peanut butter?
A: Yes, but the texture will be chunkier. Crunchy adds contrast, but if you want smooth, use creamy peanut butter.
Q: What if I don’t have a freezer space large enough?
A: The pan needs to chill until set; the refrigerator will take much longer and may not firm the fudge equally. If freezer space is limited, a shallow pan will set faster and fit better.
Q: Is the collagen necessary?
A: No. Collagen is optional. It can firm the texture slightly and add protein, but the combination of peanut butter and fat will still set into fudge without it.
Q: Will this melt on a warm day?
A: It’s solid straight from the freezer but will soften at room temperature. Keep it chilled until serving in hot conditions.
Time to Try It
This recipe lives in my freezer for a reason: it’s simple, quick, and cracks the code for a satisfying, low-carb candy. Measure, stir, chill, and slice—that’s the whole rhythm. Make a batch when you want a grab-and-go treat that feels decadent and keeps your carbs in check. Let me know how you like it—what sweetener you used, whether you added collagen, or if you tried an alternative nut butter. Small swaps tell you a lot about how flexible the recipe really is.
Low-Carb Peanut Butter Fudge (Keto)
Ingredients
Equipment
Method
- Line a 9" x 5" loaf pan or an 8" x 8" cake pan with parchment paper, leaving a few inches of overhang on two sides to lift the fudge out later.
- In a small saucepan, combine the following: 116-ounce jar unsweetened creamy peanut butter, 2/3 cup sugar-free confectioners sweetener, 1/3 cup ghee or coconut butter, 3 Tbsp Marine Collagen or beef collagen (optional), 1/8 tsp sea salt, 1 tsp pure vanilla extract (optional), and 1/2 tsp ground cinnamon (optional).
- Heat the saucepan over medium-low. Stir constantly until the mixture is fully melted and smooth, and all ingredients are well combined. Do not boil; remove from heat as soon as the mixture is evenly creamy.
- Pour the warm peanut butter mixture into the prepared pan and use a spatula to smooth it into an even layer.
- Place the pan in the freezer and chill for at least 2 hours, or until the fudge is firm and set.
- Remove the pan from the freezer, use the parchment overhang to lift the fudge out, and transfer it to a cutting board. If desired, let it sit at room temperature for a minute to ease cutting, then cut into squares with a sharp knife.
- Store leftovers in a zip-top bag in the freezer.
Notes
*I use Swerve Confectioner's Sweetener, but you can also use your favorite powdered Stevia, truvia, or monk fruit sweetener. Just be sure to use a powdered sweetener rather than granulated, as a granulated sweetener will make the fudge grainy.
