Lightly butter a 9×13 pan or line with parchment paper.
On low heat, either stove top or in microwave, melt 5 Tbsp. butter and 5 cups of marshmallows together. Stir until melted and combined.
Remove from heat. Add the cereal to the marshmallow mixture and stir until cereal is coated. Stir in 1 cup of marshmallows and ¾ cup Andes chips. Spread mixture in pan and sprinkle ¼ cup Andes chips on top. Gently press and smooth the mixture with the back of a metal spoon or a spatula sprayed with cooking spray.
Cool and cut into squares, triangles or rectangles. Any way you slice them, they will disappear quickly!