Make back rosebud petal one day in advance. Prepare buttercream icing following recipe directions. Tint portions light green, dark green, light blue, dark blue, light violet and dark violet. For each cupcake, use tip 125, cut disposable decorating bag and tinted icing to pipe 50 to 60 back rosebud petals in each light and dark icing on parchment paper-covered cake boards. Let air dry overnight. Reserve light colored icing.