Heat oil in a large Dutch oven over medium-high heat. Add ground beef and sausage, breaking it up, and cook until deeply browned, about 6 minutes.

Reduce heat to medium, push meat aside, and cook diced onion until soft, 5 minutes. Add minced garlic and cook 1 minute.

Pour in red wine and scrape up browned bits from the pot bottom. Simmer until reduced by half, about 2 minutes.

Stir in crushed tomatoes, tomato paste, oregano, basil, bay leaf, sugar, salt, and pepper.

Bring to a simmer, then lower heat and cook with the lid slightly ajar for 2 hours, stirring occasionally, until thick and glossy.

Remove bay leaf, taste and adjust salt or sugar, then ladle over cooked spaghetti and serve with Parmesan.