In advance: Use royal icing to make about 100 tip 24 swirl drop flowers with tip 2 dot centers. Make extras to allow for breakage; let dry.
Also: Make cookies. Prepare and roll out dough. Cut 1 heart with smallest heart cutter and 2 rounds each with small, medium and large round cutters from set. Bake and cool cookies.
And: Use tip 2 and full-strength royal icing to
outline heart and 1 of each size round; fill in using thinned royal icing. Let dry 48 hours.
Layer pairs of round cookies with buttercream icing; attach drop flowers around edge with icing. Using royal icing, stack and secure cookie pairs; attach upright heart to top and surround base with drop flowers.