Make cake. Prepare batter following recipe directions. Bake and cool cake according to pan package directions. Place cake on foil-wrapped cake board, cut to fit.
Ice cake. Prepare buttercream icing following recipe directions. Tint portions rose and yellow. Reserve remaining white. Use spatula and white icing to ice cake smooth.
Pipe in petals and daisy center. Use ruler and toothpick to mark each petal design area 1/2 in. from edge of cake. Use tip 5 and rose icing to pipe in petal area. Use tip 5 and yellow icing to outline and pipe in center. Pat smooth with finger dipped in cornstarch.
Decorate lattice. Use ruler and toothpick to mark the edge of each petal as a guide for lattice lines, 3/8 in. apart. Use tip 3 and rose icing to pipe lattice.
Decorate petal border. Use tip 3 and rose icing to pipe bead border around each petal design.
Decorate daisy center. Use tip 21 and yellow icing to fill in center with rosettes.
Decorate bottom border. Use tip 5 and white icing to pipe bead bottom border.
The rosette has the tight, swirling look of a rose, but is achieved in one continuous rotation, rather than with wrapped layers of petals. Single rosettes are also used as candleholders on top of a cupcake.