Step 1

To prepare the filling, soak the raisins in warm water for 30 minutes. Drain and dry them, then dice them and place them in a large bowl.

Step 2

Put the Swiss chard or spinach in a soup pot with no additional water. Cover the pot and cook over medium heat just until the leaves wilt down; this will take about 4 or 5 minutes. Drain the leaves in a colander and squeeze them with the back of a spoon to extract as much water as possible. Coarsely chop the greens and add them to the bowl with the raisins. Stir in the drained ricotta cheese, salt, nutmeg, and sugar. Mix well, then cover and refrigerate while you make the dough.

Step 3

To prepare the dough, in a food processor or bowl, mix together the flour, potato starch, salt, and sugar. Pulse in the butter or use a pastry blender to reduce the butter to small bits. Add 1 of the eggs and the water and pulse or mix until a ball of dough is obtained that is moist but holds together. If the dough seems dry, add 1 drop of water at a time until you get the right consistency. Flatten the ball into a disk and wrap it tightly in plastic wrap. Refrigerate for 1 hour.

Step 4

Preheat the oven to 375ºF. Lightly butter or spray a 9-inch tart pan with a removable bottom. Set it aside.

Step 5

Divide the dough in half. Roll out each half on a floured surface to a 12-inch circle. Fold one dough circle in quarters, then lift it and unfold it, draping it into the tart pan. Trim the dough even with the top edge of the tart pan.

Step 6

Add the filling to the tart pan, spreading it evenly. Fold the second piece of dough in quarters, place it on top of the filling at the center, then unfold the dough and trim it even with the edges. Reroll the scraps of dough and use a cookie cutter to make cutouts for the top of the pastry. Beat the remaining egg slightly and with a pastry brush paint the top crust evenly with the egg wash. With a scissors make a V in the center of the crust.

Step 7

Bake the pie for 35 to 40 minutes, or until the crust is golden brown. Cool the pie on a rack for 20 minutes before serving.