Prepare a baking sheet with a silicone baking mat or parchment paper

In a large saucepan over medium heat, combine sugar, water and corn syrup. Stir frequently.

When mixture begins to boil, add a candy thermometer. Continue cooking until mixture reaches 265°F degrees, "hard ball" stage. Add peanuts and stir.

Continue stirring frequently until mixture reaches 305°F degrees, "hard crack" stage. The color of your mixture will have darkened up rapidly at this point. Immediately remove from heat, stir in butter, vanilla, baking soda and salt.

Pour onto prepared baking sheet. Let sit undisturbed for 1-2 hours to cool and harden. Crack into desired sizes and store in an airtight container.