Chop up the tomatoes, then put them through a food mill or press them through a conical sieve. You want to separate all the juice and pulp from the seeds (a wooden pestle is handy if you use a conical sieve, or it’s possible to press so hard that you break your spatula). Set the tomato sauce aside and discard the seeds.

Heat the oil in a deep saucepan over medium heat. Add the onion and sprinkle it with about half of the salt. Cook, stirring frequently, for about 3 minutes. Turn the heat down if the onions start to brown.

Add the carrots and cook for another 5 to 6 minutes, or until the onions are soft and translucent.

Add the meat and break it up into small pieces. Sprinkle the rest of the salt and the pepper over it. Cook for 10 to 12 minutes, or until the meat is no longer pink.

Stir in the tomato sauce and the mushrooms. Raise the heat a bit and bring the sauce to a boil. Let it boil for a few seconds, then reduce the heat to a simmer. Place the lid on the pot, slightly ajar and let it cook for about 40 minutes.

After the 40 minutes are up and the sauce has thickened, stir in the sliced basil, put the lid back on (ajar), and cook for another 5 minutes.

Cook the spaghetti according to the package’s directions. Drain it and return it to the pot. Add the butter and the parmesan. Toss to combine.

Dish up the spaghetti and ladle the sauce over it. Sprinkle it with more parmesan and serve it forth.