Step 1

In a large soup pot or Dutch oven, heat the oil over medium-high heat. Add the ground beef and ground chicken and cook, breaking it up with the side of a spoon, until it is no longer pink, 6 to 7 minutes. Add the onion, celery, and carrot. Cook until the vegetables begin to soften, about 4 minutes. Add the garlic and cook for another minute. Add the red wine and cook for 3 to 4 minutes. Add the crushed tomatoes, beef broth,milk, oregano, basil, thyme, sugar, and Parmesan rind if using. Stir well.

Step 2

Bring the sauce to a boil, reduce the heat to low, cover, and simmer for 2 to 3 hours. Remove the lid and simmer for an additional 30 minutes. Remove the Parmesan rind and discard it. Season with salt and pepper.

Step 3

Serve immediately or store in the refrigerator for 3 to 4 days. This sauce can also be frozen for up to 3 months.