Old-fashioned peanut brittle is one of those classic sweets that looks impressive but is surprisingly straightforward once you understand the process. It’s crisp, deeply caramelised, and packed with roasted peanut flavour.

This version sticks to the traditional method, using a sugar syrup cooked to hard crack stage, then finished with butter and baking soda for that light, snappy texture. It’s not complicated, but it does reward a little preparation and attention.

If you’ve ever wanted to try candy-making at home, this is a great place to start. The results are far better than store-bought, and once you’ve made it once, it’s a recipe you’ll come back to year after year.

If you enjoy making classic sweets at home, this peanut brittle sits right alongside some of my other go-to recipes, like chocolate fudge, caramel fudge, and English toffee. These are the kinds of treats I come back to when I want something reliable, well-tested, and easy to share.

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Why You’ll Love This Recipe

Uses simple pantry ingredients with big flavour payoff
Classic crunchy texture with a rich caramel finish
Keeps well and makes a great homemade gift
Easier than it looks once you know the steps
A reliable, traditional recipe that actually works

Ingredients & Substitutions

The printable recipe card below has the full ingredients list and instructions.

White granulated sugar: The backbone of the brittle. Avoid substituting with brown sugar, as it changes the texture and flavour.
Glucose syrup or light corn syrup: Helps prevent crystallisation and keeps the brittle smooth rather than grainy. Either works equally well.
Water: Used to dissolve the sugar and control the cooking process early on.
Raw peanuts: They are cooked and toasted in the syrup itself, giving better flavour than pre-roasted nuts. You can use salted or unsalted, but keep it consistent with your butter choice.
Salted butter: Adds richness and balances the sweetness. Unsalted butter works too, just add a pinch of salt.
Vanilla extract: Rounds out the caramel flavour.
Baking soda: Essential for texture. It aerates the brittle, making it lighter and easier to bite.

Makyla’s Recipe Tips

Candy-making is much easier when everything is ready before you start. Once the syrup reaches temperature, there’s no time to measure or hunt for tools.
A candy thermometer makes this recipe far more reliable, especially if you’re new to sugar work. If the temperature is too low, the brittle won’t set properly; too high, and it can taste bitter.
Use a heavy-based saucepan to help prevent hot spots and uneven cooking. Thin pans can cause the sugar to scorch.
If your brittle spreads unevenly, resist the urge to keep smoothing it, letting it set naturally gives the best snap.

How to Make Old-Fashioned Peanut Brittle

Step 1: Prepare Your Setup
Butter a large baking sheet generously or line it with baking paper. Set it on a heatproof surface. Make sure all your ingredients are measured, unwrapped, and within reach. Once the syrup is ready, things move quickly, and there’s no time to pause.

Step 2: Cook the Sugar Syrup
Add the sugar, glucose (or corn syrup), and water to a heavy-based saucepan. Place over medium heat and stir gently until the sugar has completely dissolved, and the mixture looks clear. Once dissolved, stop stirring. Continue cooking, allowing the syrup to bubble steadily, until it reaches the soft-crack stage (about 280°F) on a candy thermometer.

Step 3: Add the Peanuts
Carefully stir in the peanuts. Continue cooking, stirring occasionally, until the mixture deepens to a rich golden amber colour and reaches hard crack stage (around 300°F).
Watch closely at this point: the temperature rises quickly, and the sugar can burn if left unattended.

Step 4: Add the Flavourings
Remove the pan from the heat. Immediately add the butter, vanilla, baking soda, and salt.
Stir quickly and confidently. The mixture will foam up and lighten in colour. This is exactly what you want, and it gives the brittle its crisp, airy structure.

Step 5: Spread and Cool
Pour the hot mixture straight onto the prepared baking sheet. Tilt the tray or use a buttered spatula to spread it into a thin, even layer. Don’t overwork it! The less handling, the better the texture. Leave to cool completely, then break into pieces by hand.

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Troubleshooting Tips

My brittle didn’t set hard
The syrup likely didn’t reach the hard-crack stage. A candy thermometer makes a big difference here, as the sugar needs to be hot enough to set once cooled fully.

My brittle tastes burnt
The temperature went too high or rose too quickly. Once you’re close to the hard crack stage, stay close and watch carefully as it can burn in seconds.

My brittle is grainy
This usually happens if the sugar crystallises early on. Make sure the sugar is fully dissolved before you stop stirring, and avoid scraping sugar crystals from the sides of the pan.

The mixture foamed too much
That’s normal when you add the baking soda. Just stir quickly and pour! Don’t panic or overmix.

It’s too thick to spread
Work quickly, but don’t fight it. Tilting the tray usually works better than trying to smooth it flat with a spatula.

Storage Instructions

Store peanut brittle in an airtight container at room temperature
Keep away from heat and humidity to maintain crunch
Do not refrigerate, as moisture will soften the brittle
Keeps well for up to two weeks if properly sealed

Equipment

Candy Thermometer

Ingredients

2 cups white granulated sugar
1 cup glucose syrup or light corn syrup
1/2 cup water
2 1/4 cups peanuts raw & skin on
4 tablespoons salted butter 58g
2 teaspoons vanilla extract
1 1/2 teaspoons baking soda

Instructions

Butter a large baking sheet generously or line it with baking paper. Set it on a heatproof surface.
Make sure all your ingredients are measured, unwrapped, and within reach. Once the syrup is ready, things move quickly, and there’s no time to pause.
Add the sugar, glucose (or corn syrup), and water to a heavy-based saucepan. Place over medium heat and stir gently until the sugar has completely dissolved, and the mixture looks clear.
Once dissolved, stop stirring. Continue cooking, allowing the syrup to bubble steadily, until it reaches soft crack stage (around 280°F) on a candy thermometer.
Carefully stir in the peanuts. Continue cooking, stirring occasionally, until the mixture deepens to a rich golden amber colour and reaches hard crack stage (around 300°F).
Watch closely at this point — the temperature rises quickly, and the sugar can burn if left unattended.
Remove the pan from the heat. Immediately add the butter, vanilla, baking soda, and salt.
Stir quickly and confidently. The mixture will foam up and lighten in colour. This is exactly what you want and is what gives the brittle its crisp, airy structure.
Pour the hot mixture straight onto the prepared baking sheet. Tilt the tray or use a buttered spatula to spread it into a thin, even layer. Don’t overwork it — the less handling, the better the texture.
Leave to cool completely, then break into pieces by hand.

Nutrition