1 ½ cups unsalted peanuts
Butter a large baking sheet or line with parchment paper.
In microwave-proof bowl (we used glass), combine peanuts, sugar, corn syrup and salt, then microwave for about 4-5 minutes, until the mixture is bubbling very vigorously. You can stir midway through cooking if you like.
Stir in butter and vanilla and put the mixture back in the microwave until it turns light gold color, about 2-3 minutes more. Remove and add baking soda to mixture and stir (the mixture will foam up quite a bit).
Quickly pour onto the buttered baking sheet. Tilt baking sheet from side to side to spread brittle as thinly as possible, then let stand until cold and hard – about 2 hours. Break up and enjoy!
Note: This nutty number can be stored in an airtight container at room temperature for up to 1 month. You can also substitute peanuts for any other kind of nut like almonds, cashews or walnuts.