Easy Double Decker Fudge

1 cup peanut butter chips
1 (14 ounce) can sweetened condensed milk, divided
2 tablespoons butter or margarine, softened
1 cup semisweet chocolate chips
1 teaspoon vanilla extract, divided

Line 8-inch square pan or 9 x 5-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 HIGH (100%) 1 minutes or until chips are melted and mixture is smooth when stirred; stir in 1/2 teaspoon vanilla extract. Immediately pour and spread evenly into prepared pan.

Microwave bowl with chocolate chips at HIGH 1 minutes or until chips are melted and mixture is smooth when stirred; stir in remaining 1/2 teaspoon vanilla extract. Immediately pour and spread evenly over peanut butter layer; cool. Cover. Refrigerate until firm.