Dahlia flowers are a wonderful addition to cakes and cupcakes, and they're beautiful in almost any color. Use specialty decorating tip 81 to create stand-up petals that make it look like your flower is blooming.
Add three tablespoons confectioners' sugar to one cup decorator icing. Mix until medium consistency is achieved. Prepare decorating bag with coupler, tip 12, and prepared icing. Pipe mound, about 1/2 in. high, on wax paper-covered flower nail.
Using tip 81, hold bag at 90 degree angle with rounded end of tip towards outside of mound. Pipe three petals around top of mound, overlapping slightly and curving over top.
Hold bag vertical to surface with rounded end of tip toward outside of mound. Pipe row of 5 to 6 petals around first row, standing straight up and lining up with height of petals in first row.
Continue piping second row of 8 to 9 petals and third row of 10 to 11 petals, each row of petals measuring slightly longer than the previous row. Petals in the third row should fan out slightly, creating an open flower.
Pipe 1 to 3 more rows of petals, each row fanning out from previous row, but still slightly raised. Continue until flower is full.