In a large heavy-bottomed pot, heat a 2-count of olive oil over medium heat. Add the onions, celery, carrots, and garlic and cook for about 10 minutes, stirring, until the vegetables are very tender but not browned.
Raise the heat a bit. Take the ground veal and beef, break it up into chunks and add it to the pan. Cook, breaking up the clumps with a wooden spoon, until the meat is no longer pink. Add the wine and simmer until the wine has evaporated. Then add the tomatoes and stock and season with salt and pepper. Lower the heat and simmer very slowly for 2 to 2 1/2 hours, stirring now and then, until the sauce is very thick. Now add the milk - the milk will make the meat nice and tender - and simmer again until thickened, another 20 to 30 minutes. Taste again for salt and pepper. Mash the sauce against the side of the pan to really blend it. Transfer half of the sauce to containers and refrigerate for up to a week, or freeze for up to several months.
Bring a big pot of lightly salted water to a boil for the spaghetti. When you're ready to serve, drop the spaghetti into the boiling water and cook until tender yet firm ("al dente", as they say in Italian) 7 to 8 minutes. Drain and put the spaghetti into a big pasta bowl. Return the sauce remaining in the pot to a simmer and stir in the ricotta cheese. Pour the sauce over the drained spaghetti and give it a good toss. Garnish with a handful of grated Parmigiano, the basil, and a drizzle of olive oil. Pass more grated cheese at the table.