Clean and wash the spinach and chard, then cook them in a little salted water. Strain the two kinds of greens, let them cool down and then squeeze them well to remove the water. Chop them with a knife. Pile the flour up on your work surface, or a pastry board and form a “well” in the centre, put the softened butter and salt in it and start rubbing it in with your hands. When the mixture resembles “breadcrumbs”, pile it up again, form a well in the centre and pour the warm water into it. Amalgamate everything with your hands and then knead the dough until you have a smooth ball. Wrap it in cling film and let it rest for about half an hour in a cool place.

In the meanwhile clean the spring onions: Use a knife to cut off the green part and the roots, slit the outer “skin” lengthwise and remove it. Slice the spring onions in half lengthwise and then chop them finely. Cut the pancetta into thin slices, and then into small pieces. Chop the parsley, put it in a frying pan with the chopped onion, bacon and olive oil, and cook over a low heat. Sprinkle with the nutmeg, stir and, as soon as the onion softens and the pancetta begins to brown, add the chopped spinach and chard. Stir again and continue cooking for 15 minutes. Then turn off the heat, leave to cool and stir in 7-8 tablespoons of grated pecorino cheese. Now take the dough that was resting and divide it two parts, one slightly larger than the other. Roll out the larger piece with a rolling pin until it’s about 2 mm thick (and roughly 3 cm larger than the diameter of the baking tin you’re going to cook it in) and lay it in the tin, lined with greaseproof paper. Make sure the dough adheres to the sides well, prick the bottom here and there with a fork and then fill it with the mixture in the frying pan. Roll out the other piece of dough and use it to cover the filling. Fold the excess dough over all the way around, forming a “rope” to seal the edge of the savoury pie. Beat the egg yolk with 2 teaspoons of water and brush it over the surface. Prick the dough here and there and sprinkle the remaining grated pecorino on top. Bake the “Erbazzone” in a preheated oven, at 200 °C, for roughly 30 minutes. If it should begin to brown too much, cover it with kitchen foil. Allow to cool before serving.