Line 8 by 8 baking pan with foil. spray foil with non-stick cooking spray. Melt chocolate chips in a glass bowl in the microwave, stirring at 15 second intervals til melted. Stir in the chopped candybar and marshmellows until coated. Lightly stir in the frosting to create a marbling effect. Spread into foil pan and chillabout 1 hour til set. The foil will sift right out. Flip over on cutting board and remove foil. Slice and enjoy!