Heat the oil and 6 tablespoons butter in a heavy 5-quart Dutch oven over medium heat until the butter melts and stops foaming. Toss in the onion and cook, stirring frequently, until the onion is softened and translucent, about 5 minutes.Dump in the celery and carrot and cook, stirring to coat them with the oil and butter, for 2 minutes. Add the ground chuck, a very healthy pinch of salt, and a good amount of pepper. Crumble the meat with a wooden spoon and cook, stirring occasionally, until the meats has lost its raw red color.
Reduce the heat to low. Pour in the milk and simmer gently, stirring frequently, until the liquid has cooked away completely, about 1 hour. Stir in the nutmeg. Pour in the wine and gently simmer, stirring frequently, until it has evaporated, about 1 1/4 hours.
Add the tomato purée or crushed tomatoes and stir well. When the tomato puree begins to bubble, turn down the heat so that the sauce cooks at the lowest of simmers with just an intermittent bubble breaking through the surface.
Cook, uncovered, for 3 hours or more, stirring from time to time. While the sauce is cooking away, there’s a chance that it’ll start drying out somewhat. To keep the sauce from sticking to the bottom of the pot and scorching, add 1/2 cup water if necessary, just know that it’s crucial that by the time the sauce has finished simmering, the water should be completely evaporated, and the fat should separate from the sauce. Take a spoonful—or two. Season with salt and pepper to taste. Serve with your favorite pasta.