Chocolate and Butterscotch Fudge

Preparation : Line 8-inch square pan with foil. In small microwave-safe bowl, place butterscotch chips and 1/2 cup sweetened condensed milk; set aside. In medium microwave-safe bowl, place chocolate chips, remaining sweetened condensed milk and vanilla. Microwave at HIGH (100%) 1 minute; stir until chips are melted. Stir in walnuts. Spread into prepared pan. Microwave butterscotch chips at HIGH 45 seconds; stir until chips are melted. Spread evenly over chocolate layer. Refrigerate until firm. Remove from pan. Peel off foil; cut into squares. Store in refrigerator. Makes about 4 dozen pieces.