microwave peanut brittle! - Fail proof microwave recipe. 1 cup sugar 1/2 cup light corn syrup (Karo) 1 Tbsp butter 1 tsp vanilla 1 cup peanuts (I use lightly salted cocktail peanuts) 1 tsp baking soda Combine sugar and syrup in a microwave safe bowl (I use a glass bowl), stir. Microwave on high for 5 minutes. Add butter, vanilla and peanuts; stir. Microwave on high for 1 minute 30 seconds. Remove bowl from microwave and quickly stir in baking soda. Immediately pour mixture onto parchment paper, aluminum foil or a Silpat. Spread into a rectangle and let cool for 1 hour. Break into pieces and enjoy!