Make roses on day in advance. Prepare royal icing following recipe directions. Tint violet. Use violet icing, flower nail and pre-cut squares to pipe 70 roses with tip 3 bases and tip 101 petals. Let dry on cake boards.
Make cake. Prepare batter following recipe directions. Bake and cool 2-layer cake, 4 in. high oval cake.
Decorate cake. Prepare buttercream icing following recipe directions. Tint violet and light violet. Use spatula and violet icing to ice cake smooth.
Use tip 127D, 16 in. disposable decorating bag and light rose icing to pipe ruffle around base of cake. Use tip 6 and light rose icing to attach roses to side of cake as well as to pipe message on top of cake.