01 - Heat olive oil in a large heavy-bottomed pot over medium heat. Add onion, carrot, and celery. Sauté for 6-8 minutes until vegetables are softened and fragrant.
02 - Stir minced garlic into the vegetable mixture and cook for 1 minute until fragrant, being careful not to burn it.
03 - Add ground beef to the pot, breaking it up with a wooden spoon. Cook for approximately 8 minutes until fully browned and no longer pink.
04 - Pour in red wine and simmer for 2-3 minutes, scraping up any browned bits from the bottom of the pot to incorporate the fond.
05 - Stir in tomato paste, crushed tomatoes, beef broth, oregano, basil, bay leaf, salt, and pepper. Bring the mixture to a gentle simmer.
06 - Reduce heat to low. Partially cover and simmer for 45-60 minutes, stirring occasionally, until sauce thickens considerably and flavors meld together.
07 - Stir in milk or cream during the final 10 minutes of simmering for added richness. Taste and adjust seasoning as needed.
08 - Meanwhile, cook spaghetti in a large pot of salted boiling water until al dente. Reserve 1/2 cup of pasta cooking water before draining.
09 - Remove and discard bay leaf from the sauce. Toss spaghetti with the Bolognese sauce, adding reserved pasta water if needed to achieve desired consistency. Serve hot with grated Parmesan and fresh parsley.