Prawn & spinach lasagne
For the filling
Roll the lasagne as thinly as possible. With a knife, cut into sheets of 8 x 11cm/3 1⁄2 x 4 1⁄2in and let them rest on dry tea towels for at least 15 minutes.
Bring a large saucepan of water to the boil. Add the salt, and slip in the pasta, two or three pieces at a time, leaving to cook for 1 minute. Remove with a slotted spoon, and immerse immediately in cold water. Lay the pasta on damp tea towels.
To make the filling, put the spinach in a large deep pan with no water. Cook, tossing occasionally, for 5–10 minutes. Remove from the heat, chop finely and set aside.
Warm the butter in a frying pan and add the onion. Sauté over a medium heat for 4 minutes. Add the prawns and sauté quickly, stirring to cook evenly. Remove the pan from the heat and stir in the chopped spinach and salt.
Preheat the oven to 200°C/400°F/Gas mark 6.
Combine the tomato and béchamel sauces. Select a 25 x 35cm/ 10 x 14in baking dish. Smear a very thin layer of sauce on the bottom of the baking dish. Carefully place a layer of the pasta over the sauce, to cover the entire area. Smear a thin layer of sauce over the pasta. Spoon some of the spinach and prawn mixture over it, and sprinkle with some Parmesan. Repeat the process of layering, ending with a layer of pasta, topped with sauce and cheese.
Bake for about 20 minutes or until the sauce forms a light golden crust. Remove the dish from the oven and leave to stand for 10 minutes before serving, cut into slices.