Gather 1 cup granulated sugar, 1/2 cup light corn syrup, 1/4 cup water, 1 cup roasted peanuts, 2 tablespoons butter, 1 teaspoon vanilla extract, and 1 teaspoon baking soda
Line a baking sheet with parchment paper or a silicone mat
Combine sugar, corn syrup, and water in a heavy saucepan
Cook over medium heat, stirring until the sugar dissolves
Continue cooking without stirring until the mixture reaches hard crack stage, about 300°F to 310°F
Add the peanuts and stir constantly until the mixture turns golden brown
Remove the pan from the heat
Stir in the butter, vanilla extract, and baking soda quickly
Pour the mixture onto the prepared baking sheet
Spread it thinly with a spatula if needed
Let it cool completely
Break into pieces once hardened