Preheat oven to 350 degrees. Cut buns in half and scrape out excess bread in the center. Spread 1 Tablespoon honey mustard on each bun , then layer on ham and cheese. Wrap each sandwich in foil, leaving the top open.
Mix together melted butter and garlic powder, then brush over tops of pretzel sandwiches. Close foil, then bake for 20 minutes, or until cheese is melted, and ham is hot.