1 tablespoon olive oil
1 medium yellow onion, finely chopped
2 celery stalks, finely chopped
1 medium carrot, finely chopped
2 to 3 cloves of garlic, minced
2 tablespoons tomato paste
1 1/2 to 2 pounds ground beef
2 teaspoons kosher salt
1/2 teaspoon dried thyme (or 1 teaspoon fresh thyme)
1/2 teaspoon dried oregano (or 1 teaspoon fresh oregano, minced
1/2 teaspoon pepper
1/8 teaspoon nutmeg
1 cup milk (whole or 2%)
1 cup white or red wine
2 (28-ounce) cans of whole peeled tomatoes
1 bay leaf
To serve:
Spaghetti or other pasta, cooked
Shredded Parmesan cheese
Heat the olive oil in a Dutch oven or large skillet over medium heat. Add the onion, celery, and carrot, and cook until the onion is translucent and all the vegetables have softened, 6 to 8 minutes. Add the garlic and the tomato paste, and cook until the garlic is fragrant, about 30 seconds. (If your skillet isn't big enough to also accommodate the beef at this point, transfer the vegetables to the slow cooker and continue cooking the beef by itself.)
Add the beef, breaking it apart with your spoon and cooking until it is just browned. Stir in 1 teaspoon salt along with the thyme, oregano, pepper, and nutmeg.
Stir in the milk and bring it to a rapid simmer. Continue simmering until the milk has reduced completely and very little liquid remains, about 10 minutes. Stir in the wine and simmer again until reduced completely, about 10 minutes. Using a slotted spoon, transfer the beef mixture to the bowl of a 6-quart (or larger) slow cooker.
Open the cans of tomatoes and strain through a strainer, reserving the juices. Transfer the tomatoes to the slow cooker, squishing them in your fist or mashing them against the side of the slow cooker to break them down into small pieces.
Add the bay leaf to the slow cooker and stir everything together. The mixture should have a thick, saucy consistency, neither overly soupy or too dry. If it looks dry, mix in a little of the reserved tomato juices until it looks sauce-like. If it looks too soupy, don't worry about it right now — you can let excess liquid evaporate at the end of cooking.
Cover the slow cooker and cook on LOW for 6 to 8 hours. (See below for oven-cooking instructions.)
In the last half hour of cooking, check the sauce. If it looks soupy, remove the lid to allow any excess liquid to evaporate and reduce the sauce. If it looks a little dry, stir in some of the reserved tomato juices. The finished sauce should be thick and creamy.
Serve the sauce over pasta with Parmesan sprinkled on top, or layer it into a lasagna. Leftovers will keep refrigerated for 5 days or ca