Bake and cool cake. Ice inside ears, paws and feet smooth (lighten portion of chocolate with white buttercream). Using tip 4, pipe outline mouth; outline and pipe in eyes and nose (smooth with finger dipped in cornstarch). Using tip 7, outline and pipe in banded trims of outfit (smooth with finger). Cover outfit with tip 16 stars; pipe tip 7 initial. Cover bear with tip 17 stars.