Preheat the oven to 375°F (190°C).
In a small bowl, combine the softened butter, minced garlic, chopped parsley, salt, black pepper, dried oregano, and dried basil. Mix well to create the garlic butter spread.
Place the Italian bread halves cut side up on a baking sheet. Spread the garlic butter mixture evenly over both halves of the bread.
In a large mixing bowl, combine the ground beef, breadcrumbs, grated Parmesan cheese, egg, milk, garlic powder, onion powder, salt, and black pepper. Mix until all ingredients are well incorporated.
Form the meat mixture into approximately 16 small meatballs, about 1 inch in diameter.
Place the meatballs on top of the garlic buttered bread halves, spacing them evenly.
Spoon the marinara sauce over the meatballs, covering them generously.
Sprinkle the shredded mozzarella cheese evenly over the meatballs and sauce.
Bake in the preheated oven for 20 to 25 minutes, or until the meatballs are cooked through (internal temperature of 160°F or 71°C) and the cheese is melted and bubbly.
Remove from the oven and let cool for 5 minutes before slicing and serving.