Keto Peanut Brittle (Snaps Clean, Never Chewy, 1.6g Net Carbs)
- Total time
- 45 minutes
- Makes
- 12 servings (2 pieces)
- Net carbs
- 1.6g
- Calories
- 106
My first sugar-free brittle bent. I lifted a piece off the tray, it sagged in my fingers like warm taffy, and the next morning the whole sheet had fused back into one sticky slab inside the container.
It tasted fine. It just was not brittle. And that is the complaint you see under nearly every keto peanut brittle recipe: chewy, tacky, or grainy, never the clean glassy snap you remember.
Three things fixed it. A thermometer, a half teaspoon of baking soda, and keeping the finished candy cold. This version uses six ingredients, makes 24 pieces, and comes in at 1.6g net carbs for two of them.
Why This Keto Peanut Brittle Snaps
It has to reach 300°F. That is the hard crack stage, where almost no water is left in the syrup. At 270°F it sets into something you can bend. At 300°F it sets into something that shatters. Guessing by color does not work with allulose, which browns earlier than sugar does, so the thermometer is not optional here.
Baking soda makes it light. Stirred in off the heat, it reacts with the hot syrup and fills it with tiny bubbles. Those bubbles are why good brittle breaks cleanly and does not pull at your teeth. Leave it out and you get a dense, hard sheet that is closer to a lollipop.
Allulose, and the fridge. Allulose melts and caramelizes like sugar, which is why it is the right sweetener for candy. Erythritol sets hard too, but it recrystallizes as it cools and leaves the brittle sandy. The trade-off with allulose is that it draws moisture out of the air, so the finished brittle lives in the refrigerator, not in a tin on the counter.
Recipe Overview
- Prep Time: 5 minutes
- Cook Time: 10 minutes
- Cooling: 30 minutes
- Total Time: 45 minutes
- Makes: 24 pieces, 12 servings of 2
- Net Carbs: 1.6g per serving
- You need: a candy thermometer
Ingredients
| Ingredient | Quantity | Notes |
| Granulated allulose | ½ cup (96 g) | Not erythritol, see above |
| Unsalted butter | ¼ cup (57 g) | Cut into pieces |
| Fine sea salt | ¼ tsp | |
| Vanilla extract | 1 tsp | Added off the heat |
| Baking soda | ½ tsp | Measured out before you start |
| Dry-roasted salted peanuts | 1 cup (146 g) | Already roasted |
Use roasted peanuts. Old-fashioned brittle cooks raw peanuts in the syrup for several minutes. This syrup reaches temperature quickly, and raw peanuts would come out pale and soft in the middle, so they go in already roasted.
The butter is unsalted because the peanuts already carry plenty. If yours are unsalted, raise the salt to ½ teaspoon.
Recipe Timing
| Order | Step | Time |
| 1 | Line the sheet, measure everything | 5 minutes |
| 2 | Melt and cook the syrup to 300°F | 8–10 minutes |
| 3 | Vanilla, baking soda, peanuts, spread | under 1 minute |
| 4 | Cool until hard | 30 minutes |
Step-by-Step Instructions
1. Set up everything first
Line a rimmed baking sheet with parchment and lightly butter an offset spatula. Measure the vanilla, the baking soda and the peanuts into separate small bowls beside the stove. Once the syrup hits temperature you have about thirty seconds before it starts to set, and there is no time to hunt for a measuring spoon.
2. Melt the butter and sweetener
In a heavy saucepan over medium-low heat, melt the unsalted butter. Add the granulated allulose and the fine sea salt and stir until the sweetener has dissolved and the mixture looks smooth. If a layer of butter separates on top, keep stirring gently. It comes back together as it heats.
3. Cook it to 300°F
Clip on the candy thermometer, raise the heat to medium and bring it to a steady bubble, stirring often so nothing catches on the bottom. Cook until the thermometer reads 300°F and the syrup is a deep amber, about 8 to 10 minutes from the start.
Watch it closely past 280°F. Allulose darkens quickly at the end, and a sharp, bitter smell means it went too far. Make sure the tip of the thermometer sits in the syrup and not on the bottom of the pan, or it will read high.
4. Vanilla, then baking soda, then peanuts
Take the pan off the heat. Stir in the vanilla extract, which will hiss and spit, then sprinkle in the baking soda and stir fast. The syrup foams up and turns paler and opaque. That is exactly what you want. Fold in the peanuts straight away, two or three turns, until they are coated.
5. Spread it thin and leave it alone
Tip everything onto the parchment and spread it with the buttered spatula to about ¼ inch, keeping the peanuts in a single layer. Spread it once. Going back over it after it starts to set knocks the air out and leaves streaks.
Leave it at room temperature for 30 minutes, until it is completely hard and the underside releases from the paper. Then lift it and break it into about 24 pieces with your hands.
Recipe Tips and Variations
If it bends, it did not get hot enough. That is the cause almost every time. A new thermometer is cheaper than a ruined batch, and you can test yours in boiling water: it should read 212°F at sea level.
For a harder snap, replace 2 tablespoons of the allulose with powdered erythritol. It sets firmer and holds up better out of the fridge, at the cost of a faint cooling note.
Other nuts. Roasted almonds, cashews or pecans all work, one cup in place of the peanuts. Pecans brown fast, so add them the moment the pan comes off the heat.
Spiced. Add a pinch of cayenne with the baking soda, or scatter flaky salt over the top straight after spreading so it sticks.
Serving Suggestions
Serve it straight from the fridge, on a plate rather than in a bowl, so the pieces stay apart. It is good beside coffee, broken over a scoop of keto ice cream, or packed into small cellophane bags with a tag as a holiday gift. Tell the person it lives in the refrigerator.
If you want a contrast on the same plate, my keto toffee is a buttery cousin: a butter toffee poured over almonds with a layer of chocolate on top, softer and richer where this one is light and sharp.
Storage and Troubleshooting
Refrigerator: airtight, with parchment between the layers, for up to 1 month. Freezer: up to 3 months. It can be eaten straight from frozen.
At room temperature it softens, because allulose pulls moisture from the air. An hour on a party table is fine. A week in a tin on the counter is not.
Grainy or sandy: the sweetener was erythritol, or erythritol-based, and it recrystallized. Bitter: it went past 300°F or the pan had a hot spot. Flat and dense: the baking soda was old, or it was stirred in before the pan came off the heat.
Frequently Asked Questions
Can I make keto peanut brittle without a thermometer?
You can try, but it is the most common reason it turns out chewy. Allulose goes dark before it reaches hard crack, so the usual color cue reads as done too early. A thermometer takes the guesswork out completely.
Why is my sugar-free brittle sticky the next day?
It was left at room temperature, or stored in a container that was not airtight. Allulose candy takes on moisture from the air. Keep it sealed in the refrigerator and it stays crisp.
Can I use erythritol instead of allulose?
Not on its own. Erythritol sets hard, but it recrystallizes as it cools and the brittle comes out gritty. A small amount mixed with allulose, as in the tip above, is fine.
How many carbs are in keto peanut brittle?
Two pieces are 1.6g net carbs and 106 calories, almost all of it from the peanuts. Allulose is not counted, in line with how it is treated across this site.
More Keto Candy and Treats
- Keto Buckeyes — peanut butter balls dipped in dark chocolate, no oven needed, 2.8g net carbs each.
- Keto Chocolate Truffles — a dark ganache rolled and coated, each one topped with a coffee bean.
- Keto Pecan Chewies — chewy pecan bars at 1.5g net carbs, for when you want the opposite of brittle.
- Keto Peanut Butter Cookies — three ingredients and one bowl, the fastest peanut fix on the site.
Recipe Card
Building a holiday dessert table? My keto pecan pie has a gooey filling that never turns gritty, and it pairs well with a plate of this brittle on the side.
Keto Peanut Brittle
Equipment
- Heavy saucepan 2 quart
- Candy thermometer essential
- Rimmed baking sheet lined with parchment
- Offset spatula lightly buttered
Ingredients
- 1/2 cup granulated allulose 96 g, not erythritol
- 1/4 cup unsalted butter 57 g, cut into pieces
- 1/4 tsp fine sea salt
- 1 tsp vanilla extract
- 1/2 tsp baking soda measured out before you start
- 1 cup dry-roasted salted peanuts 146 g
Instructions
- Set up: Line a rimmed baking sheet with parchment and lightly butter an offset spatula. Measure the vanilla extract, baking soda and dry-roasted salted peanuts into separate small bowls beside the stove.
- Melt: In a heavy saucepan over medium-low heat, melt the unsalted butter. Add the granulated allulose and fine sea salt and stir until dissolved and smooth.
- Cook to hard crack: Clip on a candy thermometer, raise the heat to medium and cook at a steady bubble, stirring often, until it reads 300°F and the syrup is deep amber, about 8-10 minutes in total. Keep the thermometer tip off the bottom of the pan.
- Aerate: Remove from the heat. Stir in the vanilla extract, then the baking soda, stirring fast as it foams and turns paler. Fold in the peanuts immediately.
- Spread: Pour onto the parchment and spread once with the buttered spatula to about 1/4 inch thick, peanuts in a single layer.
- Cool and break: Leave at room temperature 30 minutes, until completely hard, then break into about 24 pieces. Store airtight in the refrigerator.
Notes
Keep cooking
