Using a paper towl, lightly butter a 9x13 baking pan. Over low heat, melt the semisweet and butterscotch chips, stirring until smooth. Stir in peanut butter and remove from heat. Let cool slightly, then stir in mini-marshmallows. Spread into baking sheet and refrigerate until firm. Cut into 1-2 inch squares. Let sit for 5 minutes before serving.
Not a NESTLÉ®-tested recipe.