Blanch broccoli and leeks and cool them in ice water to conserve their colour.
Cut the lasagna sheets to the size of your dish. Mix cold maffioso sauce with the vegetables.
Cover the bottom of the dish with a thin layer of sauce, then the first sheet of lasagna, followed by the pieces of salmon and cover finally with the sauce-vegetable mixture. Repeat this operation to have a minimum of 3 layers and finish with a layer of sauce without too many pieces of salmon and cover finally with grated Parmesan.