Grease a large baking sheet well with butter or line with a silicone baking mat and set aside.

In a large microwave-safe glass bowl, stir together sugar and corn syrup until combined.

Microwave on high for 4 minutes, then carefully stir and microwave for another 3-4 minutes until the mixture turns light golden brown.

Carefully stir in peanuts and butter, then microwave for 1-2 more minutes until the mixture is a deep golden color.

Quickly stir in vanilla and baking soda (the mixture will foam up dramatically).

Immediately pour the mixture onto the prepared baking sheet and spread as thin as possible using a greased spatula.

Let cool completely for at least 30 minutes, then break into irregular pieces and store in an airtight container.