Put the prosciutto in water for about 12 hours, changing the water at least two or three times. Remove all the rind, scrape well and wipe it with a rough cloth.

Prepare the pastry for the crust, sprinkling the flour onto the work surface and kneading it with the freshly melted butter, a whole egg, a handful of salt and the water needed to obtain thick, elastic pastry.

Leave it to rest for about 2 hours.
Roll the pastry out into a sheet about half a centimetre thick, put the Parma ham in the middle, and wrap it well: close the edges by pressing them with your fingers and sticking them together using some egg white.

Brush the pastry with the rest of the egg yolk and bake it for about 40 minutes.
As soon as the pastry is golden, place it on a serving plate and serve immediately, cutting the Parma ham at the table.

If there are leftovers, this ham is also excellent served cold.