Turkey Meatballs with Whole Wheat Spaghetti and Tomato Sauce

Name: Turkey Meatballs with Whole Wheat Spaghetti and Tomato Sauce
Ingredients: 2 tablespoons olive oil; 2 medium onions, chopped; 3 celery ribs, chopped; 1 red bell pepper, stemmed, seeded and chopped; 2 cloves garlic, minced; 1 (28-ounce) can crushed tomatoes, with juices; Kosher salt and freshly ground pepper; 1 pound ground turkey; 1 (10-ounce) package frozen chopped spinach, thawed, excess moisture squeezed-out; 1/2 cup quick-cooking (not instant) oatmeal; Worcestershire sauce; 1/2 cup grated Parmesan cheese, plus more for serving; 12 ounces whole wheat spaghetti (recommended: Barilla Plus)