At least 2 days before decorating cake, make dark blue and light blue royal icing drop flowers using tip 225 (225 flowers were used for this cake as shown - make additional in case of breakage); add tip 2 yellow dot flower centers. Allow to dry completely.
Bake your favorite 2-layer cake recipe or mix in square pan. Cool cake in pan on wire rack 10 minutes. Remove from pan and cool completely. Wrap cake board cut to size with Fanci-Foil. Arrange cake on prepared cake board.
Ice cake smooth in buttercream. Pipe tip 17 top and tip 21 bottom rosette borders. Pipe tip 21 icing mound on top corner of cake and down side (this will support the flower cascade). Attach flowers on icing and each other with tip 2 dots of icing. Fill in tip 352 leaves around flowers.