Put the flour and salt in a large mixing bowl. Add the cold cubed lard and rub it into the flour with your fingertips until the mixture looks like coarse, uneven breadcrumbs with some pea-sized pieces still visible.

Add the cold wine (or water) a little at a time, mixing with a fork and then your hands just until the dough comes together. It should be smooth but not sticky. Do not overwork it.

Shape into a flat disc, wrap in clingfilm, and refrigerate for 30 minutes.

Bring a large pot of well-salted water to a boil. Add the chard and spinach and blanch for 3 minutes until wilted and vivid green. Drain immediately and spread on a tray to cool slightly.

Once cool enough to handle, gather the greens in a clean kitchen towel and twist and squeeze as hard as you can until virtually no water comes out. Chop the squeezed greens finely with a knife.

Heat the olive oil in a skillet over medium heat. Add the pancetta and cook for 2 to 3 minutes until the fat renders. Add the onion and cook for 5 minutes until pale and soft, then add the garlic and cook for 1 minute until fragrant.

Add the chopped greens to the pan, stir to combine with the soffritto, and cook for 2 minutes. Remove from the heat and let cool to room temperature.

Stir in the beaten eggs, Parmigiano, nutmeg, and black pepper. Taste and add salt carefully, keeping in mind the cheese is already salty. The filling should hold its shape loosely when pressed.

Heat the oven to 200 C / 390 F. Lightly grease a 30 x 20 cm rectangular baking tin with lard or olive oil.

Divide the chilled dough into two pieces, one slightly larger than the other. On a lightly floured surface, roll the larger piece into a rectangle about 2 to 3 mm thick, large enough to line the base and sides of the tin with a small overhang.

Lift the dough into the tin, pressing it gently into the corners without stretching it. Trim any excess leaving about 1 cm overhang.

Spread the filling evenly over the base, pressing it down lightly to remove air pockets.

Roll the second piece of dough to the same thickness and lay it over the filling. Press the edges of the top and bottom crusts together firmly, then fold and crimp the edge to seal.

Prick the top all over with a fork at 2 cm intervals. Brush the surface with melted lard or olive oil.

Bake in the center of the oven for 35 to 40 minutes until the top crust is pale golden and firm. The edges will be slightly deeper in colour.

Transfer to a wire rack and cool for at least 15 minutes before cutting into squares or rectangles.