In a heavy Dutch oven or large heavy-bottomed pot over medium heat, melt the butter with the olive oil. Add the onion and cook, stirring frequently, until the onion is translucent, about 5 minutes.

Add the carrot, celery, and garlic and cook, stirring frequently, until softened and fragrant, about 2 minutes more.

Crumble the veal, pork, and beef into the pot. Season with fine sea salt. Reduce the heat to low and cook, stirring frequently, until the meat has rendered most of its fat and is just beginning to brown, about 3 minutes.

Add the wine and increase the heat to medium. Cook, stirring occasionally, until the wine has evaporated, about 8 minutes.

Decrease the heat to low, add the tomato paste, stir to combine, and cook, stirring frequently, for 20 minutes. Season to taste with salt and pepper.

Add the stock and increase the heat if necessary to reach a gentle simmer. Simmer until the stock has reduced by half and the sauce is thick and moist, about 45 minutes longer.

Bring a large pot of water to a boil for the pasta. When the water is boiling, salt it with coarse salt (see page 51) and add the pasta. Cook until the pasta rises to the surface of the water (see page 51).

When the pasta is cooked, drain it in a colander, then transfer it immediately to the serving bowl. Top with the remaining sauce and toss vigorously to combine. Serve immediately with grated cheese on the side.