Preheat your oven to 350°F (175°C) and lightly grease your baking dish.

In a large skillet, heat olive oil over medium heat. Add bell peppers, onion, and mushrooms and sauté for about 5 minutes until tender.

Stir in roast beef, garlic powder, salt, and pepper. Cook for an additional 3-5 minutes.

Lay out provolone cheese slices overlapping slightly to create a layer.

Spoon the beef and vegetable mixture onto each cheese slice and roll tightly, seam side down.

Place the roll-ups seam side down in the baking dish and bake for about 10 minutes until cheese melts.

Allow to rest for 5 minutes, then slice into pieces and serve warm.