Preheat your oven to 350°F (175°C). Gather your ingredients and equipment.

In a preheated skillet over medium heat, add the olive oil and sauté the sliced green bell pepper, onion, and mushrooms for about 5 minutes until they soften.

Add the roast beef to the skillet with the vegetables. Add garlic powder, salt, and pepper, stirring well and cooking for an additional 3-5 minutes.

Lay out the provolone cheese slices flat on a clean surface.

Place a scoop of the beef and vegetable mixture on each provolone slice, leaving space around the edges.

Roll each provolone slice tightly around the filling and place seam-side down in a baking dish.

Bake the roll-ups in the oven for 10 minutes until the cheese is melty and bubbly.

Remove from the oven and let the roll-ups cool for a few minutes before serving warm.