Make brownies. Prepare batter following recipe directions. Bake and cool brownies in silicone mold supported by cookie sheet. Insert sticks, leaving 5 in. extended at bottom.
Decorate brownies. Place brownies on parchment paper-covered board. Tint portions of icing green, red and black. Reserve remaining white.
Use tip 3 and red icing to fill in triangle bow loops and dot knot. Pat smooth with finger dipped in cornstarch. Use tip 3 and green icing to pipe outline collar. Use tip 3 and red icing to pipe dot collar studs. Use tip 3 and white icing to pipe dot eyes. Use tip 3 and black icing to pipe dot pupils and nose and outline mouth.
Attach antlers. Use knife to cut pretzel twists for two antlers. Insert antlers in brownies.