Chop carrots, celery and onions. Cook onion in oil and butter over medium heat until translucent. Add carrots and celery, cook 2 minutes more, stirring to coat vegetables.
Add the ground beef, veal and pork, salt and pepper to taste. Cook until meat is no longer pink.
Add the milk and let it simmer gently, stirring frequently, until it has bubbled away completely.
Add in wine and nutmeg, stir well. Let simmer until the wine has evaporated, then add the tomatoes and stir thoroughly to coat all ingredients well. When the mixture begins to bubble, turn the heat down so low that the sauce is barely simmering, and cook for @ 3 hours.
It should be very thick when done. You can separate any fat that remains before serving over tagliatelle or your preferred pasta.