Baked Bologna Sliders

nonstick cooking spray
3 tablespoons yellow mustard
2 tablespoons mayonnaise
1 tablespoon sweet pickle relish
1 tablespoon hot sauce
1 (12-ounce) package Hawaiian slider rolls, split in half lengthwise
8 ounces sliced American cheese (12 slices)
1 (12-ounce) package sliced bologna
4 tablespoons unsalted butter, melted
1/2 teaspoon garlic salt

Preheat the oven to 350 F. Spray a baking dish with nonstick cooking spray.
Mix the mustard, mayonnaise, relish and hot sauce together in a small bowl.
Place the bottom of the rolls cut-side up — being careful not to break them apart — in the baking dish. Spread the mustard mixture across both cut sides of the rolls. Lay 6 slices of cheese, overlapping slightly, on top of the spread, then lay all of the bologna on top of the cheese. Top with another layer of cheese and then cover with the tops of the rolls. Brush the tops of the rolls with butter, then sprinkle with the garlic salt.
Cover the baking dish with aluminum foil. Bake for 10 minutes, then uncover and bake until the rolls are toasted and the cheese is melted and oozing, about 5 minutes more. Transfer to a plate or board, cut apart and serve.