Prepare Peach Melba Cake batter following instructions; bake in petal pan following recipe instructions. Cool in pan on cooling grid 15 minutes; remove from pan and cool completely. Cut cake board to shape of pan; cover with Fanci-Foil.
Prepare Raspberry Filling following recipe instructions. Stack bottom cake layer on prepared cake board; with tip 12 and buttercream icing, outline layer about 1 in. from edge. Spoon filling inside outline; add top cake layer. Prepare cake for fondant by lightly icing with buttercream.
Tint fondant yellow; roll out 1/8 in. thick; cover cake with fondant. Imprint fondant on cake tops and sides with butterfly cutters from sets.
Tint buttercream icing burgundy, rose, blue, orange and black. Working in small areas at a time, outline butterfly imprints with tip 3 and tinted icing; immediately brush out lines of icing toward center of pattern area with damp brush. Work in quick, short strokes. Clean brush with water after brushing each flower to create distinct lines of icing. For larger butterflies, repeat with second color. Add butterfly body with tip 5 black icing and tip 3 black antenna.
Pipe tip 22 yellow buttercream shell bottom border around cake. Insert butterfly icing decorations into border. Add tip 3 yellow buttercream bodies and heads.