In advance: Make flowers. Using dark rose royal icing, make 32 tip 101 roses, with tip 5 bases. Make extra to allow for breakage and let dry overnight. Pipe a tip 5 pull-out spike on rose bottoms to insert into cake. Let dry.
Also: Make cookie. Prepare and roll out dough. Cut cookie using second largest heart cutter in set. Bake and cool. Outline with tip 3 and royal icing. Flow in with thinned royal icing. Let dry overnight. Write message with black FoodWriter. Attach lollipop stick to back with royal icing. Let dry.
Bake, cool and fill cake following pan directions. Place cake on foil-wrapped cake board. Ice smooth in rose buttercream. Using Cake Dividing Set, divide cake into eighths. With toothpick, mark scallops 1 1/2 in. deep. Insert roses at markings. Using tweezers, position Sugar Pearls 1 in. apart on cake top and above roses, securing with piping gel.
Pipe tip 5 bead bottom border in white buttercream. Overpipe beads with tip 125 ruffled ribbon bottom border in white buttercream. Insert heart cookie in cake top.