Prepare the Garlic Butter: Melt the garlic butter by microwaving or heating on the stove. Set aside.

Cook the Beef and Vegetables: In a large skillet, heat oil over medium-high heat. Sauté onions and bell peppers for 4-5 minutes until softened. Add beef and cook for 5-7 minutes, until browned. Season with salt and pepper.

Prepare the Bread: Slice the Italian bread lengthwise, leaving a hinge. Hollow out the bread, leaving about 1/2 inch around the edges. Brush the inside with garlic butter.

Stuff the Loaf: Stuff the loaf with the beef and vegetable mixture, spreading it evenly. Top with shredded provolone cheese.

Bake: Preheat oven to 375°F (190°C). Wrap the loaf in foil and bake for 10-12 minutes until the bread is crispy and the cheese is melted. Open the foil for the last 3 minutes for a crispier crust.

Serve: Remove from the oven, slice, and garnish with fresh parsley. Serve immediately.