1 stick soft butter
1 tsp. dry mustard
1 tsp. poppy seed
1 tsp. grated onion
12 slices baked ham (thick)
12 slices Swiss cheese
12 hamburger buns

Make a paste of the first 4 ingredients and put on the bottom of the bun. Top with ham, cheese and top of bun. Wrap in foil and bake 15 minutes at 325 degrees until cheese melts. (Can also be made the day before.)