Combine butter, horseradish, mustard and poppy seeds. Mix thoroughly. Open all of the hamburger buns and brush both sides of the inside with the poppy seed dressing. Place two ounces of ham and one slice of cheese on bottom part of the bun. Repeat with the remainder of the buns. Close the tops of the buns and brush more of the poppy seed dressing on the outside tops and bottoms of the buns. Tightly wrap each sandwich in aluminum foil and freeze.
To cook, preheat oven to 400-degrees and place sandwich, still tightly wrapped in foil, directly on the center rack for approximately 30 minutes until center is hot and cheese is melted.
Yield: 8 sandwiches