1/4 c. butter
1 1/2 tsp. prepared mustard
1/2 tsp. poppy seed
4 hamburger buns
4 thin slices ham
4 thin slices Swiss cheese

Combine first 3 ingredients. Spread on buns. Place slice of ham and cheese on bun. Wrap with bun separately in foil. Bake 20 minutes at 350 degrees.