Keto Peanut Brittle – Crunchy, Sweet, and Low-Carb

This keto peanut brittle gives you everything you love about the classic treat—crunch, caramel flavor, and roasted peanut goodness—without the sugar crash. It’s surprisingly simple to make at home with a few smart swaps and a candy thermometer. If you’ve been missing old-school brittle on a low-carb lifestyle, this version checks all the boxes.

It sets up firm, breaks cleanly, and stores well for snacking or gifting. Grab a saucepan and let’s make a batch you’ll want to keep on repeat.

Keto Peanut Brittle - Crunchy, Sweet, and Low-Carb

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Prep Time 15 minutes mins

Cook Time 30 minutes mins

Total Time 45 minutes mins

Servings: 4 servings

Ingredients Method

Ingredients

  

• 1 cup roasted, salted peanuts (or unsalted; see notes)
• 1 cup allulose sweetener (granulated)
• 2 tablespoons butter (salted or unsalted)
• 2 tablespoons water
• 1 tablespoon sugar-free syrup (optional, for extra gloss and stretch)
• 1 teaspoon vanilla extract
• 1/2 teaspoon baking soda
• 1/4 teaspoon fine sea salt (skip if peanuts are salted)
• Neutral oil or butter for greasing the pan

Method

 

1. Prep the pan: Lightly grease a rimmed baking sheet or line it with a silicone mat. Keep your baking soda, vanilla, butter, and peanuts measured and ready. Once the syrup hits temperature, you’ll need to move fast.
2. Combine sweetener and water: In a medium heavy-bottomed saucepan, add allulose and water. Stir gently just to moisten. If using sugar-free syrup, add it now.
3. Cook the syrup: Set over medium heat. Do not stir once it starts simmering. Clip on a candy thermometer and let it cook until it reaches 300°F (hard crack). This usually takes 8–12 minutes. If the edges darken too quickly, lower the heat.
4. Add butter and peanuts: Remove from heat and quickly stir in the butter until melted, then add peanuts. Stir to coat. Return to low heat for 15–30 seconds if needed to keep it fluid, but don’t overcook.
5. Flavor and aerate: Take the pan off the heat. Stir in vanilla and salt. Sprinkle baking soda over the mixture and stir briskly. It will foam and lighten in color—that’s what produces the brittle’s airy crunch.
6. Spread it out: Immediately pour onto the prepared baking sheet. Use a greased spatula to spread into a thin, even layer, about 1/4 inch thick. Work quickly before it sets.
7. Cool and break: Let cool completely, 20–30 minutes. Once firm, break into shards. Taste and adjust with a sprinkle of flaky salt if you like.

What Makes This Recipe So Good

• Authentic crunch: Using allulose creates that classic snappy texture without crystallizing like some sweeteners do.
• Low in net carbs: Smart ingredient choices keep it keto-friendly while still tasting like the real thing.
• Simple process: A handful of pantry staples and a candy thermometer are all you need.
• Customizable: Swap peanuts for other nuts and add warm spices, vanilla, or a sprinkle of flaky salt.
• Great for gifting: Break into shards, wrap, and share—no one will guess it’s sugar-free.

Ingredients

• 1 cup roasted, salted peanuts (or unsalted; see notes)
• 1 cup allulose sweetener (granulated)
• 2 tablespoons butter (salted or unsalted)
• 2 tablespoons water
• 1 tablespoon sugar-free syrup (optional, for extra gloss and stretch)
• 1 teaspoon vanilla extract
• 1/2 teaspoon baking soda
• 1/4 teaspoon fine sea salt (skip if peanuts are salted)
• Neutral oil or butter for greasing the pan

How to Make It

1. Prep the pan: Lightly grease a rimmed baking sheet or line it with a silicone mat. Keep your baking soda, vanilla, butter, and peanuts measured and ready.
   

   Once the syrup hits temperature, you’ll need to move fast.

2. Combine sweetener and water: In a medium heavy-bottomed saucepan, add allulose and water. Stir gently just to moisten. If using sugar-free syrup, add it now.
3. Cook the syrup: Set over medium heat.
   

   Do not stir once it starts simmering. Clip on a candy thermometer and let it cook until it reaches 300°F (hard crack). This usually takes 8–12 minutes.

   
   

   If the edges darken too quickly, lower the heat.

4. Add butter and peanuts: Remove from heat and quickly stir in the butter until melted, then add peanuts. Stir to coat. Return to low heat for 15–30 seconds if needed to keep it fluid, but don’t overcook.
5. Flavor and aerate: Take the pan off the heat.
   

   Stir in vanilla and salt. Sprinkle baking soda over the mixture and stir briskly. It will foam and lighten in color—that’s what produces the brittle’s airy crunch.

6. Spread it out: Immediately pour onto the prepared baking sheet.
   

   Use a greased spatula to spread into a thin, even layer, about 1/4 inch thick. Work quickly before it sets.

7. Cool and break: Let cool completely, 20–30 minutes. Once firm, break into shards.
   

   Taste and adjust with a sprinkle of flaky salt if you like.

How to Store

• Room temperature: Store in an airtight container for up to 2 weeks. Keep it dry; moisture softens brittle.
• Layering: Separate layers with parchment to prevent sticking.
• Freezer: You can freeze brittle in a sealed container for 1–2 months. Thaw in the container at room temp to avoid condensation.
• Avoid the fridge: Refrigerators are humid, which can make brittle tacky and soft.

Why This is Good for You

• Low-carb friendly: Allulose doesn’t spike blood sugar the way regular sugar does, keeping this treat keto-appropriate.
• Healthy fats and protein: Peanuts add plant-based protein and fats, which can help with satiety.
• Fewer additives: Homemade means you control the ingredients—no hidden sugars or corn syrup.
• Portionable: Breaking it into shards makes it easy to enjoy a small piece when you want something sweet.

Common Mistakes to Avoid

• Using the wrong sweetener: Erythritol tends to crystallize and can make the brittle gritty.
  

  Allulose is the best choice for a classic texture.

• Skipping the thermometer: Guessing leads to soft or burnt brittle. Aim for 300°F for that clean snap.
• Over-stirring early on: Once the syrup starts simmering, don’t stir or scrape the sides. This helps prevent crystals from forming.
• Forgetting to prep: Have everything measured and ready.
  

  The window between perfect and overcooked is short.

• Spreading too thick: A thin layer sets faster and gives the signature brittle crunch. Thick layers can turn chewy.

Variations You Can Try

• Spicy peanut brittle: Add 1/4 teaspoon cayenne or chili powder with the vanilla for a warm kick.
• Cinnamon-vanilla: Stir in 1/2 teaspoon ground cinnamon with the baking soda for a cozy twist.
• Nut swap: Use almonds, pecans, or a mix. Chop larger nuts for easier spreading.
• Sesame crunch: Replace half the peanuts with toasted sesame seeds for a toasty, nutty flavor.
• Chocolate-dipped: Once cooled, dip pieces in melted sugar-free dark chocolate and let set.
• Salted brittle: Finish with a light sprinkle of flaky sea salt while it’s still warm for sweet-salty contrast.

FAQ

Can I use erythritol or monk fruit sweeteners?

Erythritol-based sweeteners tend to recrystallize and create a gritty texture in brittle.

If you use a monk fruit blend, make sure it’s allulose-based. For the best snap and clean bite, stick with pure allulose.

Do I really need baking soda?

Yes. Baking soda reacts with the hot syrup to create tiny bubbles, which lighten the candy and give it that brittle, airy crunch.

Without it, the texture can be dense and glassy.

My brittle turned out soft. What happened?

It likely didn’t reach hard crack stage. Make sure the syrup hits 300°F.

Also, humidity can soften brittle, so store it in an airtight container and avoid making it on very humid days if possible.

Can I make this dairy-free?

Yes. Use coconut oil or a plant-based butter instead of dairy butter. The texture and flavor remain excellent, though you’ll get a slightly different richness.

What if I only have unsalted peanuts?

That’s fine.

Add the 1/4 teaspoon salt as listed, and taste a small shard after it cools. If you want more contrast, sprinkle a touch of flaky sea salt on top while it’s still warm.

Is allulose keto-friendly?

Allulose is a rare sugar that isn’t metabolized like regular sugar and has minimal impact on blood glucose. Most people on keto count it as zero net carbs.

Always factor in your personal macros and tolerance.

Can I double the recipe?

You can, but work quickly and use a large, heavy pot. Doubling increases the time the syrup stays hot, and it can darken faster. It’s often easier to make two single batches back to back.

Final Thoughts

Keto peanut brittle proves you don’t have to give up classic candy for a low-carb lifestyle. With allulose, a thermometer, and a few minutes of focused attention, you’ll get crisp, glossy shards that taste just like the original. Keep a jar on the counter for a quick treat, or wrap a bundle to impress a friend. Once you see how simple it is, this recipe will earn a permanent spot in your holiday and everyday snacking routine.