Step 1: Prepare Your Workspace

Before you start cooking, set up your workspace completely. Line a large rimmed baking sheet with parchment paper or a silicone baking mat. Have all your measured ingredients ready and within arm’s reach – once the candy starts cooking, things move quickly and you won’t have time to measure. Place the butter, baking soda, vanilla, and salt in small separate bowls near your stove. This preparation is crucial for success.

Step 2: Combine Sugar, Corn Syrup, and Water

In a heavy-bottomed 3-quart (or larger) saucepan, combine the sugar, corn syrup, and water. Stir gently with a wooden spoon or heat-resistant spatula until the sugar is mostly dissolved. Don’t worry if some sugar crystals remain on the sides of the pan – they’ll dissolve as the mixture heats.

Step 3: Cook the Sugar Mixture

Place the saucepan over medium-high heat. If using a candy thermometer, clip it to the side of the pan now, making sure the bulb doesn’t touch the bottom of the pan. Bring the mixture to a boil, stirring occasionally to prevent scorching. Once it reaches a full boil, stop stirring and let it cook undisturbed. This prevents crystallization.

Continue cooking until the mixture reaches 250°F (121°C) on your candy thermometer. This is called the hard ball stage. If you don’t have a thermometer, this will take about 10-12 minutes of boiling. The mixture will be clear and bubbling rapidly.

Step 4: Add the Peanuts

Once the mixture reaches 250°F, carefully stir in the raw peanuts. The temperature will drop when you add the cold peanuts – this is normal. Continue cooking, stirring frequently now to prevent the peanuts from burning on the bottom. The peanuts will start to roast and become fragrant.

Cook, stirring constantly, until the mixture reaches 300°F (149°C). This is called the hard crack stage. The mixture will turn a beautiful golden amber color. If you don’t have a thermometer, this takes about 5-7 minutes after adding the peanuts. You’ll know it’s ready when the mixture turns a deep golden color (like honey) and you can smell the peanuts roasting. You can also test by dropping a small amount into cold water – it should immediately harden and crack.

Step 5: Add Butter, Vanilla, Salt, and Baking Soda

Remove the pan from heat immediately when it reaches 300°F. Working quickly but carefully, stir in the butter until it melts completely. Then add the vanilla and salt and stir to combine. Finally, add the baking soda and stir vigorously. The mixture will foam up dramatically – this is exactly what should happen! The foaming action is what creates those air pockets that make the brittle crispy rather than tooth-breakingly hard. Keep stirring for about 5-10 seconds until the baking soda is fully incorporated and the mixture is lighter in color and foamy.

Step 6: Pour and Spread

Immediately pour the hot brittle mixture onto your prepared baking sheet. Work quickly – the candy starts to set as soon as it hits the cool pan. Using a buttered metal spatula or the back of a wooden spoon, quickly spread the brittle as thin as possible across the pan. You want it about 1/4 inch thick for the best texture. Don’t worry about making it perfectly even – rustic and irregular is part of peanut brittle’s charm.

Step 7: Cool Completely

Let the peanut brittle cool completely at room temperature. This will take about 30-45 minutes. Don’t try to speed up the process by putting it in the refrigerator, as this can cause the brittle to absorb moisture and become sticky. You’ll know it’s completely cool when it’s no longer warm to the touch and has a hard, glassy appearance.

Step 8: Break into Pieces

Once completely cool, break the brittle into irregular pieces. You can do this by hand – just lift the whole sheet off the pan and break it apart. Or use the handle of a butter knife to tap and crack it into shards. There’s something wonderfully satisfying about breaking peanut brittle! Aim for pieces that are 2-3 inches across, though they’ll naturally break wherever they want to.