Preheat oven to 375°F (190°C). In a skillet, heat olive oil over medium heat and sauté peppers and onions for about 5 minutes, until softened. Set aside to cool slightly.

In a large bowl, combine ground beef, breadcrumbs, egg, milk, Worcestershire sauce, garlic powder, salt, and pepper. Press half the meat mixture into a loaf pan, layer with 4 slices of provolone, then add the sautéed peppers and onions. Cover with the remaining meat, pressing to seal the edges.

Bake for 45–50 minutes. In the last 5 minutes, place the remaining 4 slices of provolone on top and bake until melted.

Let rest for 5–10 minutes, then garnish with parsley and serve warm.