Rinse the 1.2 kg octopus under cold water, then remove the beak, eyes, and internal organs if they have not already been removed.

Cut the cleaned octopus into bite-size pieces, separating the tentacles and cutting the head into small pieces.

Finely dice the 2 celery stalks, 2 carrots, and 1 onion to make a soffritto base.

Finely chop the fresh parsley, reserving a small amount for the final garnish.

Heat 3 tbsp extra-virgin olive oil in a large frying pan over medium heat.

Add the diced celery stalks, carrots, and onion to the hot oil, then cook for about 8 minutes until softened.

Add the octopus pieces to the soffritto, then brown them for 5 minutes over medium-high heat.

Pour in the 750 ml red wine and scrape the bottom of the pan to release the browned cooking juices.

Bring the wine to a gentle simmer, then cook uncovered for about 20 minutes to reduce it.

Stir in the 300 g tomato passata and most of the chopped fresh parsley.

Season the ragù with 1/2 tsp salt and 1/4 tsp black pepper, adjusting carefully because the sauce will reduce.

Cover the pan partially and simmer the octopus ragù over low heat for about 70 minutes until the octopus is tender.

Bring a large pot of salted water to a rolling boil during the last 15 minutes of ragù cooking.

Cook the 400 g spaghettone pasta in the boiling water until very al dente, about 2 minutes less than the package instructions.

Reserve 240 ml pasta cooking water, then drain the spaghettone pasta.

Transfer the drained spaghettone pasta to the octopus ragù and toss it over medium heat.

Add reserved pasta cooking water a little at a time, then toss for 2 minutes until the sauce coats the pasta.

Divide the pasta among 4 plates and garnish each serving with the reserved fresh parsley.