Line a large cookie sheet with parchment paper or a silicone mat. In a deep microwave-safe bowl, combine sugar and corn syrup. Mix thoroughly and microwave on HIGH for 4 minutes.
Stir in peanuts and microwave on HIGH until the mixture is light brown, about 3 to 5 minutes longer.
Stir in butter and vanilla until combined. Microwave on HIGH until peanuts are lightly browned, about 1 to 2 minutes longer.
Stir in baking soda until mixture is light and foamy. Pour onto prepared pan and cool 30 minutes. Break into pieces to serve and store in an airtight container.
Baking soda: Adding baking soda to the hot sugar syrup makes lots of tiny air bubbles that give the candy the porous, honeycomb texture it's famous for.
Yield: This recipe makes about 1 pound of peanut brittle.
Grease the pan: Butter a baking sheet or line it with parchment so the brittle doesn’t stick.
Let it flow: Don't try to spread it with a spatula; just let it flow like lava.
Clean-up: Spray the bowl and the spoon or spatula with a non-stick spray before you use them. It will make the hot brittle less sticky and make clean up a little easier.
Microwaves: Each appliance is a little different and your results may vary.
Storage: Store covered at room temperature for up to 2 months.
Chocolate peanut brittle. Sprinkle a layer of semi-sweet chips as soon as you pour the hot brittle onto the pan. Then wait a minute for the chips to melt and gently spread the chocolate over the surface. Amazing!
Without corn syrup. Unfortunately, there isn’t a good method for microwave peanut brittle without corn syrup.