Step 1

Make the sauce: Heat olive oil in large saucepan over medium heat. Add onion and garlic and cook, stirring, until translucent. Using your hands, crush tomatoes and add to saucepan, along with their juices; stir to combine. Add bay leaves, salt, and pepper. Cover, bring to a boil, and immediately reduce to a simmer.

Step 2

Make the meatballs: Place beef, cheese, breadcrumbs, parsley, onion, eggs, salt, and pepper in a large bowl. Gently mix together by hand to combine. Wet hands with cold water and roll meat mixture into 1 3/4-inch balls.

Step 3

Heat olive oil in a large nonstick skillet over medium heat. Working in batches if necessary, place meatballs in skillet. Cook until browned on all sides, but not cooked through. Transfer meatballs to a paper towel-lined baking sheet to drain.

Step 4

Transfer meatballs to sauce and gently stir from the bottom up to coat with sauce. Cover and let simmer for 30 minutes. Uncover and reduce heat. Continue cooking, stirring every 15 minutes, for 3 hours more. Serve with spaghetti, sprinkled with more cheese, if desired.