Peel and thinly slice the 2 kg Montoro onions.

Chop the 2 celery stalks and 2 carrots into rustic medium pieces.

Cut the 1 kg beef muscle into large bite-size chunks.

Heat the 60 ml extra-virgin olive oil in a large heavy pot over medium heat.

Add the chopped celery stalks and carrots, then sauté until lightly softened, about 5 minutes.

Add the beef muscle chunks and brown them for 10 minutes, stirring regularly.

Add all sliced Montoro onions and stir them through the browned meat.

Add the fresh parsley, salt, and black pepper, then mix well.

Cover the pot and simmer over very low heat for about 240 minutes, stirring occasionally until the onions become creamy and the beef falls apart.

Bring a large pot of salted water to a boil while the Genovese sauce finishes cooking.

Break the 400 g Neapolitan ziti pasta by hand into shorter pieces.

Cook the broken Neapolitan ziti pasta in boiling salted water until al dente, about 10 minutes.

Drain the cooked pasta, reserving a little cooking water.

Toss the drained pasta with the Genovese sauce until evenly coated and creamy.

Grate the 50 g Parmigiano Reggiano over the pasta and serve immediately.