For the elixir of roasted chestnuts and mackerel bones:
Roast the mackerel carcasses and chestnuts in an oven at 180 degrees for 20 minutes, coaxing out their deeply toasted essence. Allow them to cool, then enclose everything in a sous-vide cooking bag with water, allowing them to gently steam at 90 degrees for 3 hours. Clarify the broth through a fine etamine cloth, and infuse with the sea-scented algae for 10 minutes. Next, introduce the two soy sauces and the precious anchovy colatura. Once cooled, let the chestnut flour infuse for 15 minutes, then filter once more through the etamine.

For the smoked mackerel:
Carefully clean the mackerel and extract two pristine fillets; debone them meticulously, and submerge them to marinate for 45 minutes in a cure of salt, sugar, and citrus. Rinse gently under cold running water, pat dry, and cradle them in the aromatic embrace of smoldering holm oak embers.

For the kaffir lime dust:
Slowly dehydrate the kaffir lime leaves for 4 hours at 70 degrees, then grind them into a fine, fragrant powder.

For the cooking of the spaghettone:
Boil the spaghettone for 20 minutes (transcending the standard 10), then instantly arrest the cooking process, bringing it down to 0 degrees in the blast chiller. Awaken the pasta once more over the historic holm oak embers of the Antiche Carbonaie.

For the composition of the dish:
Within a shallow bowl, gently cradle the flaked mackerel. Upon it, rest the nest of roasted spaghetti and the dusting of kaffir lime leaves. Pour the warm, aromatic broth so it fills a quarter of the vessel, and, with the grace of a truffle slicer, adorn the creation with delicate shavings of raw chestnut.