Chocolate Marshmallow Mile High Squares

2 cups (12 ounce package) semi-sweet chocolate chips
1 2/3 cups (11 ounce package) butterscotch flavored chips
1/2 cup creamy or chunky peanut butter
9 cups (16 ounce package) miniature marshmallows
1 cup dry roasted peanuts

Line a 13 x 9-inch baking pan with foil.

Microwave semi-sweet morsels, butterscotch morsels and peanut butter in large, microwave-safe bowl on MEDIUM-HIGH (70%) power for 2 minutes; stir. Microwave at additional 10- to 20-second intervals, stirring until smooth.

Cool for 1 minute. Stir in marshmallows and peanuts.

Spread into prepared pan. Refrigerate until firm. Cut into squares.