Spaghetti And Meatballs

Ingredients

• 2 28-ounce cans whole peeled tomatoes in juice, drained, juice reserved, tomatoes finely chopped
• 1/2 cup (1 stick) unsalted butter
• 2 medium onions, peeled, halved through root end
• 1/2 teaspoon (or more) salt
• 1 cup fresh breadcrumbs made from crustless french or country-style bread
• 1/3 cup whole milk
• 8 ounces ground beef (15% fat)
• 8 ounces ground pork
• 1 cup finely ground (not grated) parmesan cheese
• 1/3 cup finely chopped italian parsley
• 1 teaspoon salt
• 1/4 teaspoon freshly ground black pepper
• 2 large eggs
• 2 large garlic cloves, pressed
• 1 pound spaghetti
• freshly grated parmesan cheese (for serving)