Bake and cool cakes completely. Trim hat and apron off cake.
Place cakes on cooling grid with parchment paper underneath. Pour thinned royal icing over mini cake. Tap grid gently for even coverage. Let set approximately 20 minutes. If necessary, cover with second coat and let set.
For scarf, roll out small amount of green fondant from multi-pack using pink guide rings on fondant rollers. Cut 4 in. x 1/4 in. strip. Attach to neck using damp brush. For scarf tails, cut two 3/4 in. x 1/4 in. strips from green fondant. Brush back with damp brush and attach to scarf. Roll small piece of red fondant to 1/16 in. Cut two 1/4 in. x 1/4 in. pieces. Cut fringe; attach piece to scarf tails using damp brush.
Roll two small red fondant balls for buttons. Attach using damp brush. Roll two small black fondant balls from multi-pack for eyes. Attach using damp brush. Roll four tiny black fondant balls for mouth. Attach using damp brush.
Combine small amount of red fondant with yellow fondant to make orange. Roll 1/8 in. thick log. Cut to a 5/8 in. length, then shape into a carrot. Attach using damp brush.
Form small amount of red fondant into hat with 1 in. base. Roll white fondant into a 3/16 in. log. Cut to 4 in. Attach around hat using damp brush. Roll small white ball for pompom. Attach using damp brush. Attach hat to snowman using icing.
Roll black fondant 1/8 in. thick and cut two 1 in. pieces. Make 1/4 in. cut in one end of each piece. Separate into a V-shape for branch arm. Let dry about 1 hour. Make small hole in side of cake and insert arm.