Heat cream, butter, sugars, cocoa and chocolate in saucepan over medium-low heat, stirring, until smooth and sugars are melted, 10 minutes. Remove from heat. Stir in vanilla. Serve warm. Store in refrigerator To warm, place over hot water, stirring. Makes 1-1/2 cups.
Stir 1/2 teaspoon mint extract into 1 recipe of Hot-Fudge Sauce.