Pulverize the raspberries to a fine powder in a food processor. Sift 2 teaspoons of the powder into the ready-made frosting and stir until a pink hue is achieved. Spread the frosting on top of the cake using a small offset spatula. Position two small doilies side-by-side on top of the cake and sift 1 to 2 tablespoons of the raspberry powder over the doilies. Remove the doilies to reveal the design.