Lasagne verdi alla bolognese

The day before, make about one and a half times the ragù alla bolognese recipe and weigh out 1 kg; keep it in the fridge. Before assembling, reheat it gently, stirring, until it is hot, and keep the béchamel warm too.

Start from about 1 kg–1.2 kg of fresh spinach, as bought. Wash it, boil it for 2–3 minutes in salted water, drain it and let it cool. Squeeze it in your hands, then in a cloth, until no more water comes out, and chop it as finely as you can. Weigh out 350 g after squeezing.

Check A dry, dense green paste: pressed between your fingers, no water runs out.

Heap the flour on the board and make a wide well. Put the eggs and the spinach in it, beat them together with a fork, and draw in the flour little by little until the mixture is too stiff to stir. Then knead with the heel of your hand for about 15 minutes.

Check Smooth, firm and evenly green, with no streaks: add a spoonful of flour if it sticks.

Divide the dough into four pieces and roll them out one at a time, keeping the others covered, into sheets about 1 mm thick.

Check An even thickness all over, with no thin spots that would tear in the water.

Cut the sheets into rectangles of about 15 cm × 10 cm.

Tip With practice, cut them a little smaller than the dish, so each layer needs fewer pieces.

Warm the milk. In a saucepan, melt 100 g of butter, stir in the flour and cook for 2 minutes without letting it colour. Pour in the warm milk a little at a time, whisking, then simmer gently for about 10 minutes, stirring, until it coats the back of a spoon. Season with salt and a little grated nutmeg.

Check Smooth and creamy, with no lumps, thick enough to coat a spoon.

Dip each sheet briefly in the cold water, then lay it flat on a clean white cotton or linen cloth to dry, not touching the next.

Heat the oven to 180 °C. Butter the bottom of the dish and spread a few spoonfuls each of ragù and béchamel over it.

Cover with sheets of pasta, then spread a thin layer of béchamel, plenty of ragù, a few flakes of butter and a good handful of Parmigiano. Prick the pasta 3–4 times with the toothpick, so no air bubbles form. Repeat, keeping the layers even, until you have at least 6. The ragù should be plentiful but not excessive, and the béchamel creamy and spread thin.

Check At least 6 even layers, the dish nearly full.

Tip Before you start, set aside a few spoonfuls of ragù for the base and a little for the top, then divide the rest of the ragù and most of the Parmigiano by eye by the number of layers, so you do not run out.

Lay a last sheet of pasta and spread it with a little ragù mixed with a little béchamel. Dot it with butter, sprinkle with Parmigiano, and put a flake of butter in each corner of the dish.