In a Dutch oven or large saucepan over medium-high heat, heat oil until shimmering. Add garlic cloves and sauté until browned, stirring occasionally to prevent scorching, about 3 to 4 minutes. Remove garlic and discard.
Stir in crushed tomatoes, diced tomatoes and their juice, sugar, basil, oregano, and salt and pepper to taste (I like 1/2 teaspoon salt and 1/4 teaspoon pepper).
Add meatballs to the pan, reduce heat to medium, and simmer uncovered until flavors have blended and meatballs reach an internal temperature of 155 degrees on an internal thermometer, about 10 to 15 minutes.
While the sauce is simmering, bring 4 quarts of water and 1 tablespoon salt to a boil. Add spaghetti and cook until al dente, about 10 minutes. Drain pasta well.
Serve pasta topped with tomato sauce and meatballs, garnishing with grated parmesan, if desired.