Sauté the Aromatics:
Heat olive oil in a large pot or Dutch oven over medium heat. Add onion, carrots, and celery. Sauté for 6–8 minutes until soft and golden. Stir in garlic and cook for 1 minute more.
Brown the Meat:
Add ground beef and cook until browned, breaking it up as it cooks. Season with salt and pepper.
Deglaze with Wine:
Pour in red wine and scrape up any browned bits from the bottom. Simmer for 2–3 minutes to let the alcohol cook off.
Build the Sauce:
Stir in tomato paste, crushed tomatoes, oregano, rosemary, bay leaf, and red pepper flakes if using. Bring to a simmer.
Simmer Low and Slow:
Reduce heat to low, partially cover, and simmer for at least 1 hour (up to 2 hours), stirring occasionally, until thickened and rich.
Finish with Cream:
Stir in milk or cream in the last 10 minutes of cooking for added depth and silkiness.
Serve:
Remove bay leaf. Spoon over pasta or creamy polenta, and top with fresh herbs and grated Parmesan.