• In a skillet, sauté the onion, peppers, mushrooms, and garlic in a drizzle of oil until softened. Let cool slightly.
• In a large bowl, combine the ground beef, breadcrumbs, eggs, Worcestershire sauce, salt, pepper, and half of the sautéed veggies. Mix gently until just combined.
• On a parchment-lined baking sheet, shape half of the beef mixture into a loaf base. Lay the provolone slices across the top, then cover with the remaining beef mixture. Seal the edges so the cheese stays inside.
• Bake at 375°F for 45–55 minutes, until the internal temperature reaches 160°F. Rest the meatloaf for 10 minutes before slicing.

Make the Cheese Whiz

• While the meatloaf bakes, make the sauce:
• Melt the butter in a saucepan over medium heat.
• Whisk in the flour and cook for 1 minute.
• Slowly whisk in warm milk, cooking until smooth and slightly thickened (about 3–4 minutes).
• Reduce heat to low and stir in the cheddar and American cheese until fully melted and creamy.
• Add garlic powder, paprika, and season with salt and pepper. When the sauce is ready it should be thick enough to coat a spoon.
• Slice the meatloaf, spoon the homemade Cheese Whiz generously over the top, and garnish with the reserved sautéed veggies if desired.