1. Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
2. Cut the tops off the bread loaves and hollow out the centers to create bowls. Save the removed bread for another use like homemade breadcrumbs.
3. In a small bowl, mix the olive oil, minced garlic, oregano, basil, salt, and pepper. Brush this mixture generously on the inside of each bread bowl.
4. Place the bread bowls on the baking sheet and bake for about 10 minutes until they are lightly crispy.
5. While the bread bowls are baking, cook the spaghetti according to package instructions until al dente. Drain and set aside.
6. In a large saucepan, heat the marinara sauce over medium heat. Add the cooked spaghetti and toss until well coated.
7. Spoon the spaghetti into the garlic bread bowls, then sprinkle with Parmesan and mozzarella cheese.
8. Return the filled bread bowls to the oven and bake for an additional 10 minutes, or until the cheese is melted and bubbly.
9. Garnish with fresh parsley before serving.

As someone who learned to cook from a grandmother who rarely measured ingredients, trust your instincts here. If you feel like adding more cheese or spices, go for it!