Baked Ham and Cheese Party Sandwiches

INGREDIENTS

• 3/4 cup melted butter
• 1 1/2 tablespoons Dijon mustard
• 1 1/2 teaspoons Worcestershire sauce
• 1 1/2 tablespoons poppy seeds
• 1 tablespoon dried minced onion
• 24 mini sandwich rolls
• 1 pound thinly sliced cooked deli ham
• 1 pound thinly sliced Swiss cheese