Put the oil, butter, and onion in a saucepan on a medium flame. Cook and stir the onion until translucent, about 5 minutes, then add the celery and carrots. Cook for about 2-3 minutes, stirring the vegetables to coat them well.
Add the meat and simultaneously a large pinch of Kosher salt and a few grindings of pepper. Crumble the meat with a fork and stir until it is browned and no red parts remain.
Add milk or half and half and let it simmer gently, stirring frequently until it has bubbled away, about 1 hour. Add nutmeg and stir.
Add wine and let it simmer until evaporated, about 1 hour more. Add the tomatoes and stir thoroughly. When the tomatoes bubble, lower the heat so the sauce simmers on the lowest possible flame. Cook uncovered for 3+ hours, stirring occasionally. While the sauce is cooking, it may begin to dry out and the fat separates from the actual meat so add a 1/2 cup of water when necessary, but in the end no water should be left when you serve it. Add salt and pepper to taste.
Toss with drained pasta, adding an additional tablespoon of butter and serve with grated Parmigiano-Reggiano on the side.
