Clean the leeks and remove the first 3 or 4 leaves from the leek trunk and cut them into julienne. Melt the leek trunk over low heat in a pan with butter and season. Cook slowly so that the trunk is cooked without colouring. Once the trunk is cooked, brown the leek julienne.
Place the quantity of Quattro Formaggi sauce in a pan and heat slowly. Once the sauce is hot, pour in the Parmesan and cream, season and keep warm.
Heat the Ravioli in slightly salted boiling water for 5 min. and drain.
Spread some sauce nicely on a hot plate, arrange a bed of leek julienne to place the leek trunk on top of it. Dress the ravioli and decorate with some watercress leaves.
Tip: check the cooking level (to the heart) of the leek trunk. It must be well-melted, while the julienne should be slightly crunchy in order to create a contrast between the 2 preparations.