Preheat your oven to 350°F (175°C). Gather your ingredients and have your baking dish ready.

In a large skillet, heat the olive oil over medium heat until it shimmers.

Add the sliced green bell pepper, onion, and mushrooms to the skillet. Sauté for about 5 minutes.

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

Lay the provolone cheese slices flat and evenly distribute the beef and vegetable mixture onto each slice.

Carefully roll each cheese slice tightly around the filling and place seam-side down in a greased baking dish.

Bake in the preheated oven for 10 minutes until the cheese melts and gets bubbly.

Remove from oven and let the roll-ups rest for about 5 minutes before serving.