Bake your favorite 2-layer cake recipe or mix in round pan. Cool cake in pan on wire rack 10 minutes. Remove from pan and cool completely. Assemble cake on foil-covered cake circle.
Using spatula, ice cake smooth in buttercream icing. Lightly mark icing with toothpick, dividing cake into 8ths.
Tint icing green, violet, rose, blue and orange. At each toothpick mark, if desired, trace Flower Pot shape using toothpick. Create flower pot shape with tip 6 icing lines at each division; pipe tip 47 (smooth side up) band at top rim of pot. Pipe tip 3 outline green stems; add tip 352 leaves. Add tip 233 pull-out grass bottom border. Write tip 3 message on cake top. Position candles.