In a 4-cup glass measure, combine 1/2 cup granulated sugar, 1/2 cup packed brown sugar, 1/2 cup butter or margarine, and 1/2 cup whipping cream. Microcook on 100 percent power (high) for 3 to 4 minutes or until butter melts and mixture boils, stirring every minute. Stir in 1 teaspoon vanilla. Serve immediately.
Prepare sauce as directed. Cool; cover and store in the refrigerator for up to 7 days. Reheat the sauce in a saucepan or return to 4-cup glass measure and cook on 100 percent power (high) for 1 to 1-1/2 minutes.