Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish.

Cook the vegetables: Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add onions (and peppers/mushrooms if using). Cook until soft and lightly golden, and all liquid has cooked off. Add garlic, cook 30 seconds, then transfer vegetables to a bowl.

Cook the beef: Add remaining olive oil to the skillet. Increase heat to high. Add beef in batches, seasoning lightly with salt and pepper. Cook quickly until just browned. Stir in Worcestershire sauce.

Assemble: Spread beef evenly in the baking dish. Top with cooked vegetables, then sprinkle provolone evenly over the top.

Bake: Bake uncovered for 20–25 minutes, until bubbly around the edges and cheese is fully melted.

Rest: Remove from oven and let rest for 10 minutes before slicing and serving.