In advance: Make cookies. Prepare and roll out dough. Use pattern to cut hat; use largest round cutter from set to cut 3 balloons. Bake and cool cookies. Cover with thinned royal icing ; let dry. Set hat on waxed paper. Use royal icing to pipe tip 5 number and tip 16 pull-out star pompom. Let dry. When dry, attach lollipop stick to back of hat, leaving 3 in. exposed to insert into cake.
Bake and cool cake; position on foil-covered cake board. Mark oval on tummy. Use tip 3 and buttercream to pipe in inside ears, paw pads and tummy (smooth with finger dipped in cornstarch). Print tip 3 name. Add confetti sprinkles. Use spatula to build up icing and ice muzzle smooth. Pipe in tip 3 nose and mouth; overpipe for dimension (smooth with finger). Pipe tip 5 eyes. Cover body with tip 233 pull-out fur. Insert hat. Use royal icing to pipe tip 16 pull-out star brim and to attach ribbons to balloon backs. Attach ribbons to paw with dots of icing.