In a large skillet, melt the butter over medium heat. Be careful not to let it burn; adjust the heat if necessary.

Add sliced onions and optional bell peppers to the skillet. Cook until they're soft and lightly caramelized, about 8 to 10 minutes.

Increase the heat slightly and add the thin-sliced steak. Use a spatula to break it up gently as it cooks, listening for that satisfying sizzle. Cook until the beef is no longer pink.

Keep the slider rolls connected and slice them in half horizontally like one big sheet.

Place the bottom half of the rolls in a greased baking dish. Layer provolone cheese evenly on these buns.

Spoon the beef mixture over the cheese, spreading it evenly. Top with another layer of provolone.

Add the top buns and brush them with melted butter mixed with garlic powder. Sprinkle with sesame seeds or dried parsley if desired.

Bake in a preheated oven at 350°F (175°C) until the cheese is melted and the tops are golden, about 15 to 20 minutes.

Let them sit for about 5 minutes before slicing along the bun lines.