Pour bag of white miniature marshmallows into large shallow bowl. Spoon 2 tablespoons of the frosting into small bowl; tint with food colour to desired shade of pink for nose; set aside. Pipe or spread remaining frosting on cupcakes (frosting will be slightly mounded). Press top of each cupcake into marshmallows, covering top completely. Place cupcakes on platter, fitting snugly together. Sprinkle leftover marshmallows as needed to fill in any gaps between cupcakes forming face.