Hawaiian Ham and Cheese Sliders

Details

Ingredients

• cooking spray (such as Crisco®)
• ½ cup butter
• 1 onion, minced
• 3 tablespoons Dijon mustard
• 1 tablespoon poppy seeds
• 2 teaspoons Worcestershire sauce, or more to taste
• 1 (12 count) package Hawaiian sweet rolls, split, or more as needed
• 1 pound sliced deli ham, or more as needed
• 8 slices Swiss cheese, or more as needed