Cream margarine and sugar. Add molasses. Alternate dry ingredients with water.
You'll need to make 7 templates by drawing the dimensions out on butcher paper. Use the templates as a stencil to cut the dough into the required pieces.
Two front and rear walls: 5 inches high by 8 inches long. Cut out 2 windows from each wall, and 2 1/2 by 1 1/2-inch door in one.
Two side walls shaped like a house (triangle on a square): 5 inches high by 6 inches long, with a triangle 7 inches high on top (cut all in 1 piece). Cut 1 window out of each side.
Two overhanging roof pieces: 4 1/2 inches wide by 9 inches long.
One door: 2 1/2 inches high by 1 1/2 inches wide.
Roll out into quarter inch thick sheets and cut them into the shape of your gingerbread house using the templates.
When ready to cook, start the Traeger grill on Smoke with the lid open until the fire is established (4 to 5 minutes). Set the temperature to 350 degrees F and preheat, lid closed, for 10 to 15 minutes.
Bake at 350 degrees F for 8 to 10 minutes or until lightly browned around edges. Let cool.
For frosting, whip ingredients on high speed with mixer until frosting forms peaks and holds its shape, about 5 to 7 minutes.
Assemble the house using the frosting as glue by setting them up on a cardboard base, and piping the royal icing at the joints with a medium plain tip from the inside.
Prop the sides up with glasses and let set for 30 minutes. Attach the roof pieces, using the icing in the same way.
Decorate with Royal Frosting and candy while you listen to Christmas music and visit with your friends and family.
Makes 2 large size gingerbread houses.