Preheat your oven to 375°F (190°C).
In a skillet over medium heat, add olive oil and sauté diced green bell pepper and onion for about 5 minutes until they are softened and fragrant. Set them aside after cooking.
In a large bowl, mix together ground beef, breadcrumbs, egg, milk, Worcestershire sauce, garlic powder, salt, and black pepper until well combined.
Press half of the meat mixture into the bottom of a loaf pan before layering with four slices of provolone cheese followed by the sautéed peppers and onions.
Top with the remaining meat mixture and press down firmly to seal all edges before baking it in the preheated oven.
Bake for 45-50 minutes; during the last five minutes of baking time, place four more slices of provolone cheese on top so they melt into gooey perfection.