In advance, using royal icing, make 300 tip 225 drop flowers with tip 2 dot centers. Make extras to allow for breakage and let dry. Trim 1 in. off open end of 4 sugar ice cream cones. Beginning at bottom edge, pipe tip 16 pull out stars for branches. Let dry.
Bake and cool 5 complete cupcakes and one extra bottom. Ice cupcakes tops and bottoms smooth in buttercream icing. Using Cake Divider Set, dot mark cupcake tops into 8ths 1 in. from bottom edge up to top points. On 4 of the cupcake tops, between one division section trim 1 in. off cupcake so that cake will sit flush against center cake when assembled. Set aside.
Decorate cupcake bases: Mark windows 1 1/2 x 1 in. and 2 1/2 x 1 1/2 in. doors on cupcake bases. Outine and fill in using tip 5. Smooth with finger dipped in cornstarch. Using tip 3 pipe drapes, scrolls around windows, door heart, and door knob. Add tip 2 dots. Position tops on bases. Pipe tip 3 beads on tops at division marks. Attach drop flowers with dots of icing to form garland.
Assemble cakes: Turn extra cupcake bottom upside down, position on foil-covered base board and prepare for stacked construction. Position one assembled cupcake on top. Arrange cupcakes around center stacked cupcake, positioning cut edges flush against center cake.
Ice board around cakes. Position trees. For bushes, outline cupcakes using tip 12. Overpipe for dimension. Cover with tip 16 stars. Attach drop flowers.
Make pennants: Using card stock cut out 2 in. wide x 1 in. high pennants and attach to lollipop sticks using transparent tape. Insert into castle cake tops. Attach drop flowers at insertion point.