Bake and cool 2 layer 10 x 3 in. cake (2-1 1/2 in. layers). Place on a foil wrapped cake board. Ice smooth with white buttercream icing.
Use Slide 'N Cut Edge Cutter to cut Bright Yellow Sugar Sheets! into a 6 x 6 in. square. Position square centered on cake top.
Pipe tip 8 bead bottom border with white buttercream icing.
Using punch with largest Layered Stars Cutting Insert cut six stars from Bright Green Sugar Sheets! Red Sugar Sheets! Bright Blue Sugar Sheets! Purple Sugar Sheets! Cut four stars from Bright Yellow Sugar Sheets! attach to sides and top of cake, with piping gel.
Attach letters on top of cake using Black Alphabet Sugar Sheets!