PIERCE cupcakes with wooden skewer or large fork at 1/4-inch intervals. Add boiling water to gelatin; stir 2 min. until completely dissolved. Carefully spoon over cupcakes, adding about 2 tsp. to each. Refrigerate 3 hours.
TINT whipped topping with food coloring; spread about 2 Tbsp. onto each cupcake.
CUT each large marshmallow crosswise into 5 pieces with clean kitchen shears. Dip 1 cut side of each marshmallow piece into colored sugar. Arrange 5 pieces on top of each cupcake to resemble a flower. Lightly moisten 1 side of each miniature marshmallow with water, then dip into colored sugar; place in center of marshmallow flower.