Dry Roasted Peanut Brittle

1 cup granulated sugar
1/2 cup light corn syrup
1 1/4 cups dry roasted unsalted peanuts
1 tablespoon butter or margarine
1 teaspoon vanilla extract
1 teaspoon baking soda

Generously grease baking sheet. In 2 quart microwave-proof bowl, combine sugar and corn syrup. Cook on HIGH for 4 minutes. Stir in peanuts with a wooden spoon. Cook on HIGH 4 to 5 minutes or until mixture reaches 300 degrees F on microwave-proof candy thermometer (or small amount separates into hard, brittle threads in cold water). Blend in baking soda, stir until mixture is light and foamy. Pour in baking sheet, spread quickly. As candy cools, stretch into thin sheet using buttered hands. Cool completely. Break into pieces and store in an airtight container.