Preheat your oven to 375°F (190°C).

Heat 2 tablespoons of olive oil in a large skillet over medium heat. Sauté diced green bell pepper and onion for about 5 minutes until softened.

In a mixing bowl, combine ground beef, breadcrumbs, egg, milk, Worcestershire sauce, garlic powder, salt, and black pepper. Mix gently until just combined.

Press half of the meat mixture into the bottom of a greased loaf pan. Layer with 4 slices of provolone cheese, then spread the sautéed vegetables on top.

Top with the remaining meat mixture, sealing the edges to contain the fillings.

Bake in the preheated oven for 45-50 minutes until the internal temperature reaches 160°F (71°C). Add the remaining provolone slices on top during the last 5 minutes of baking.

Remove from oven and let rest for 5-10 minutes before slicing. Garnish with fresh parsley if desired.