Cook spaghetti in a large pot of salted boiling water until al dente, then drain and set aside.

Heat olive oil in a large skillet over medium heat. Brown ground beef, breaking it up with a spoon, and drain any excess fat.

Add chopped onion to the skillet and cook until softened. Stir in minced garlic and cook until fragrant.

Pour in crushed tomatoes and tomato sauce. Stir in oregano, basil, salt, and pepper. Simmer for 15-20 minutes, allowing flavors to meld.

Preheat oven to 375°F (190°C). Carefully hollow out each bread roll, leaving a 1/2-inch thick shell.

Combine melted butter, minced garlic, and chopped parsley in a small bowl. Brush the inside and outside of each hollowed-out bread roll generously with the garlic butter.

Place buttered rolls on a baking sheet and bake for 5-7 minutes, until lightly golden and fragrant, to prevent sogginess.

Add the drained spaghetti to the simmering meat sauce and toss to coat evenly.

Spoon the spaghetti mixture generously into each toasted garlic bread bowl.

Sprinkle shredded mozzarella and grated Parmesan cheese over the spaghetti in each bowl.

Return baking sheet to the oven and bake for 8-10 minutes, until cheese is melted and bubbly and bread bowls are golden brown.

Garnish with fresh parsley, if desired, and serve hot.