Meatball Boats

For the Tomato Sauce:

2 tablespoons olive oil
1 onion, finely chopped
2 cloves garlic, minced
1 can (28 ounces) crushed tomatoes
1 teaspoon dried oregano
1 teaspoon dried basil
Salt and pepper to taste
1 tablespoon sugar (optional, to balance acidity)
For the Bread Boats:

4 large sub rolls or baguettes, halved and hollowed
2 tablespoons melted butter
1/2 teaspoon garlic powder
1/4 cup grated Parmesan cheese