In advance: Cut Roll-Out Cookie Dough using Circle Metal Cutter; cut a hole at top using narrow end of tip 4; bake and cool.
Using royal icing, pipe 20 tip 2D swirl drop flowers with tip 3 dot centers on waxed paper. Using thinned royal icing in cut parchment bag, pipe 1 and 1 1/2 in. circle faces on waxed paper; let dry.
Attach faces to cookies with royal icing. Using thinned royal icing in cut bag, pipe dot nose. Using full-strength royal icing, pipe hair with tips 3 and 13. Draw eyes and mouth with FoodWriter? markers.
Also: Make 12 branches using 18-gauge wrapped florist wire, using one 14 in. and one 10 in. length for each branch. Twist the 2 lengths together leaving 4 in. length of single wire at bottom.
Wrap with florist tape, adding 3 Green Leaves and leaving 4 in. at bottom untaped. Tape on an 8 in. wire for side branch; add 2 leaves.
Ice smooth 2-layer 12 in. round cake (3 in. high) in buttercream and prepare for
tall-tier construction, using one 6 1/2 and one 7 3/4 in. column for tree trunk.
Pipe tip 21 shell bottom border and tip 18 shell top border. Print tip 4 message. Attach flowers with icing and add tip 352 leaves.
Insert branches in center column; if all wires won't fit, attach to outside of column with melted candy, then wrap with floral tape.
Lightly ice trunk; overpipe with tip 21 stripes. Thread a 12 in. curling ribbon through hole in cookie; tie onto branches.
Drop flowers are a great way to add flowers quickly. Pipe drop flowers in buttercream directly on your cake, or pipe in royal in advance and place your flowers anywhere. Flowers will be sharper in definition when piped in royal.