Prepare the Vegetables: Heat 1 tablespoon of oil in a large pan over medium heat. Add the diced onion, bell pepper, and mushrooms. Cook until tender, about 7-10 minutes. Stir occasionally to ensure the vegetables cook evenly.
Add Garlic: Add the chopped garlic to the pan and cook for an additional minute until fragrant. Remove from heat and set aside to cool slightly.
Mix the Meatloaf Ingredients: In a large bowl, combine 2 pounds of ground beef, 1/2 teaspoon of salt, 1/2 teaspoon of pepper, 1/2 cup of cheese whiz (if using), 1 teaspoon of Worcestershire sauce, 2 tablespoons of ketchup, 2 eggs, and 1 cup of panko breadcrumbs. Add the cooked mixture of onions, bell pepper, mushrooms, and garlic. Mix everything together until well combined. You can use your hands or a spoon for this step, making sure all the ingredients are evenly distributed.
Assemble the Meatloaf: Place half of the meat mixture into a baking dish or a lined baking sheet. Press it down gently to form a base. Lay 4 ounces of provolone cheese (if using) in the center of the meat mixture, then top with the remaining meat mixture. Seal the edges well to ensure the cheese is fully enclosed within the meatloaf. Shape the loaf as desired and make sure the top is level.
Bake the Meatloaf: Place the assembled meatloaf in a preheated 350°F (180°C) oven. Bake for 50-60 minutes or until the meatloaf is cooked through and the internal temperature reaches 160°F (71°C). The meatloaf should be firm to the touch and browned on top.
Top with Provolone: Once the meatloaf is cooked, remove it from the oven. Spread the 8 slices of provolone over the top of the meatloaf. Return it to the oven and broil for 2-4 minutes, or until the cheese is melted and bubbly. Watch carefully to avoid burning the cheese.
Serve: Let the meatloaf rest for a few minutes before slicing. Serve it hot, and enjoy the creamy, cheesy, savory layers in every bite! This Philly Cheesesteak Meatloaf is perfect on its own or paired with mashed potatoes, a side salad, or your favorite vegetables.
