Place Chocolate chips, butterscotch chips, and peanut butter in 2-Qt bowl. Microwave uncovered on high (100%) until softened, 2 to 2 1/2 minutes. Stir until melted and smooth.
Mix in marshmallows and peanuts until evenly coated. Spread in buttered square baking pan 8 x 8 x 2-inches. Refrigerate until firm, at least 1 hour. Cut into bars, 2 x 1-inch.
