Put in a large pot of water with a little salt to the boil and boil the asparagus for about 3 minutes. Then strain them and pat dry with kitchen paper. Cut them into pieces with a length of 2 cm. Put in a pan 3 tbsp butter and sauté them for a few minutes. Put them in a bowl with the sauce and add their tuna cut in small pieces without oil from the can. Add 500 g Bechamel seasoned with salt, pepper and nutmeg and the remaining 100 g leave for later. Cook pasta according to package directions. Strain and add to the bowl with the fish and asparagus. Add the pecorino and 30 g Parmesan - grated. Stir gently. Grease suitable pan with 2 tbsp butter and pour the mixture. Dilute the remaining béchamel with the milk and cover the pasta well. Sprinkle with remaining Parmesan and bake in preheated oven at 200 C for 20 minutes how so melted Parmesan and form a crust. Serve still warm. * You can prepare bechamel in 3 tbsp butter fry a few tablespoons of flour, being careful not to burn and add 500 ml cold milk. Stir and allow to thicken. Season with salt and pepper.