Preheat your oven to 375°F (190°C).
In a small bowl, mix together the olive oil, garlic powder, Italian herbs, salt, and black pepper.
Cut the tops off the bread rolls and hollow out the insides, leaving about 1/2 inch of bread on the sides and bottom.
Brush the inside of each bread bowl with the garlic oil mixture.
In a separate bowl, combine the cooked spaghetti and marinara sauce, mixing well.
Fill each bread bowl with the spaghetti mixture, packing it in gently.
Top each filled bread bowl with shredded mozzarella and grated Parmesan cheese.
Place the filled bread bowls on a baking sheet and bake for 15-20 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let cool for a few minutes before garnishing with fresh basil leaves, if desired.