Before you start cooking, have all your vegetables sliced and ready to go. Heat 1 tablespoon of olive oil in a large 12-inch skillet over medium-high heat. Once the oil shimmers, add the sliced onions and bell peppers and sauté for 3 to 5 minutes until they soften and the edges start to brown. If using mushrooms, add them and cook for another 3 minutes until they turn golden.

Push the vegetables to one side of the skillet and add the ground beef to the empty space. Break it apart with a wooden spoon, creating small crumbles. Let it sit undisturbed for about 2 minutes first to develop a brown crust, then continue breaking it up and cooking for another 5 minutes total until no pink remains.

Stir in the garlic powder, Worcestershire sauce, salt, and black pepper. Mix everything together thoroughly, combining the vegetables with the seasoned beef. If your beef released a lot of grease, drain off the excess now. Cook for 2 minutes to let the flavors come together.

Reduce the heat to low and arrange all 4 provolone slices over the beef mixture, overlapping them slightly to cover the surface. Cover the skillet with a lid and let the cheese melt for 2 to 3 minutes. While the cheese melts, if you want toasted rolls, pop them in a 350°F oven for 2 minutes.

Slice your hoagie rolls lengthwise without cutting all the way through, leaving them hinged on one side.

Once the cheese has melted completely, spoon the beef and vegetable mixture generously into each hoagie roll. Serve immediately while hot.