Grease two large, rimmed baking sheets very well with butter and place them in the oven at 175˚F.
In a small bowl, combine the vanilla, baking soda, and salt. Set aside.
In a large, heavy-bottom saucepan, combine the sugar, water, and light corn syrup. Bring to a boil over medium heat, stirring constantly, until it reaches 240˚F (soft ball stage).
Stir in the peanuts and continue cooking, stirring constantly, until the mixture reaches 300˚F.
Working quickly but carefully, remove from heat and stir in the butter and baking soda mixture.
Pour half of the mixture onto each warm baking sheet.
Cool and then break into pieces. Store in an airtight container for up to two months.
Video
Notes
Safety:
Keep in mind that the peanut brittle mixture is super hot, so please be extra careful. It is helpful to have someone around to aid you while pouring the mixture on to the baking sheets.
Storage:
Separate your peanut brittle into layers using wax paper and place it in an airtight container. Store it for up to two months, preferably in a cool, dark, and dry environment.