- Line 8-inch square pan or 9x5x3-inch loaf pan with foil.
- Place peanut butter chips, 2/3 cup sweetened condensed milk and butter in medium microwave-safe bowl. Place chocolate chips and remaining sweetened condensed milk in second medium microwave-safe bowl.
- Microwave bowl with peanut butter chips at MEDIUM (50%) 1 minute or until chips are melted and mixture is smooth when stirred; stir in 1/2 teaspoon vanilla. Immediately pour and spread evenly into prepared pan.
- Microwave bowl with chocolate chips at MEDIUM 1 minute or until chips are melted and mixture is smooth when stirred; stir in remaining 1/2 teaspoon vanilla. Immediately pour and spread evenly over peanut butter layer; cool. Cover; refrigerate until firm. Remove from pan; place on cutting board. Peel off foil; cut into 1-inch squares. Store in tightly covered container in refrigerator.
NOTE: For best results, do not double this recipe.