Preheat the oven to 350°F. Grease a 9×5 inch loaf pan.
In a large bowl, combine ground beef, breadcrumbs, eggs, milk, diced green bell pepper, diced onion, garlic powder, salt, and black pepper.
Mix until just combined.
Heat olive oil in a skillet over medium heat. Add sliced onion, sliced green bell pepper, and mushrooms.
Cook until vegetables are softened, about 5-7 minutes. Stir in Worcestershire sauce, and season with salt and pepper.
Remove from heat and let cool slightly.
Press half of the meatloaf mixture into the bottom of the prepared loaf pan. Spread the cooked vegetable mixture over the meat.
Lay 6 slices of provolone cheese over the vegetable mixture, covering it completely.
Top with the remaining meatloaf mixture, pressing gently to seal the edges around the cheese.
Place the loaf pan in the preheated oven and bake for 45 minutes.
Remove meatloaf from the oven and sprinkle evenly with shredded provolone and mozzarella cheese.
Return to the oven and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.
Let the meatloaf rest for 10 minutes before slicing. Serve warm.
Notes
Recipe Tips & Tricks
Use 80/20 ground beef for the juiciest, most flavorful meatloaf. Leaner beef works but won’t be as moist.
Don’t overmix the meatloaf mixture. Mix just until combined or it becomes tough.
Sauté vegetables well so they release moisture before stuffing. This prevents liquid overflow. Let the cooked vegetables cool slightly before adding to the meatloaf so they don’t start cooking the raw meat.
Press the edges of the top meat layer to seal around the cheese filling so it doesn’t leak out.
Cover with foil while baking so the top doesn’t dry out.
Place a pan underneath the loaf pan to catch any drips so your oven stays clean.
Let it rest 10 minutes before slicing. This helps it hold together and keeps the juices inside.
Use a sharp knife for clean slices that show off all those beautiful layers.
Serve with dinner rolls to soak up all the delicious juices!