1. Center a rack in oven and heat to 350 degrees. Grease a 9x13" baking dish.
2. Using a serrated knife, slice sheet of rolls in half lengthwise (do not separate into individual pieces). Place bottom half in prepared baking dish, then top each roll evenly with ham, followed by pickles and cheese. Spread 4 tablespoons mustard over cut side of top half, then place on top of cheese.
3. Stir together butter, poppy seeds, minced onions, and remaining 1 tablespoon mustard in a small bowl, then brush over top of rolls. Cover tightly with foil and bake until sandwiches are heated through and cheese is melted, about 20 minutes.
4. Remove foil and continue to bake until tops are lightly browned, about 5 minutes. Let sliders sit 10 minutes before serving.
Source: Hannaford fresh Magazine, October - November 2021