Preheat oven to 350 degrees Fahrenheit. Lightly grease a 9x13-inch baking pan.
Use a serrated knife to slice 12 slider rolls in half, lengthwise, separating them into two slabs.
On the bottom slab, layer half of the cheese slices. Spread 1 pound leftover Mississippi pot roast on top. Sprinkle 1/2 cup banana pepper rings across the meat layer. Layer the remaining cheese on top. Place the top slab of rolls on the meat and cheese layers.
In a small bowl, stir together 1/4 cup melted salted butter, 1 tablespoon finely minced onion, and 1 teaspoon garlic powder. Brush on top of the slider rolls.
Cover the pan loosely with aluminum foil and bake in the preheated oven for 10 minutes.
Remove the foil and continue baking for an additional 10 minutes. Serve hot.
Notes
These are so good dunked into leftover pot roast au jus (all the juices) if you have any left over!
Transform any shredded beef into Mississippi pot roast sliders. Mix 1 pound shredded beef with 1 tablespoon dry ranch seasoning and 1 teaspoon onion powder.