01 - Heat olive oil in a large, heavy-bottomed pot over medium heat. Add onion, carrot, and celery. Sauté for 7-8 minutes until vegetables are soft and fragrant.
02 - Add garlic and cook for 1 minute, stirring continuously to prevent burning.
03 - Add ground beef and cook, breaking it up with a spoon, until browned and no longer pink, about 6-8 minutes.
04 - Pour in red wine, scraping any brown bits from the bottom of the pot. Simmer for 2-3 minutes until slightly reduced.
05 - Stir in tomato paste, crushed tomatoes, oregano, basil, bay leaf, salt, and pepper. Bring to a gentle simmer.
06 - Lower heat, partially cover, and simmer for 45 minutes, stirring occasionally to develop flavor.
07 - Stir in milk and simmer uncovered for another 10 minutes. Remove bay leaf. Adjust seasoning to taste.
08 - Meanwhile, cook spaghetti in a large pot of salted boiling water according to package instructions until al dente. Reserve 1/4 cup pasta water, then drain.
09 - Add drained spaghetti to the sauce, tossing with reserved pasta water until thoroughly coated. Serve immediately, topped with Parmesan and fresh herbs if desired.