Peanut Brittle

Steps

1. Butter a large rimmed baking sheet. Measure the 2 tablespoons butter, the vanilla and the baking soda into separate small bowls and set them by the stove. The last steps move fast.
2. Put the sugar, corn syrup, water and salt in a heavy 3- to 4-quart saucepan. Stir over medium heat until the sugar dissolves and the syrup boils. Clip on a candy thermometer so the tip does not touch the bottom of the pan.
3. Cook without stirring until the syrup reaches 250°F, about 15 minutes.
4. Stir in the peanuts. Keep cooking, stirring often so they do not scorch, until the thermometer reads 300°F and the syrup is a light golden amber, 8 to 12 minutes. The peanuts will smell toasted. Hot sugar burns badly, so keep children well back.
5. Take the pan off the heat. Stir in the butter and vanilla, then the baking soda. The mixture will foam up and turn lighter in color. Stir just until mixed.
6. Pour it right away onto the baking sheet and spread it as thin as you can with a buttered spatula, working fast before it sets.
7. Let it cool completely, about 1 hour, then break it into pieces.

Good to know

• Storage: layer the pieces in an airtight tin with parchment between them and keep it at room temperature for up to 2 weeks. The refrigerator makes brittle sticky.
• No candy thermometer? Drop a little syrup into a glass of ice water. At 300°F it forms hard threads that snap when you bend them.
• If you can only find roasted peanuts, use unsalted ones and warm them in a 200°F oven while the syrup cooks. Cook the syrup to 300°F without them, take it off the heat, stir in the warm peanuts with the butter and vanilla, then add the baking soda.