Remove dough from refrigerator and preheat oven to 400° F with a rack in the center.

Wash and dry the chard leaves well. Remove stems and save for another use. Chop leaves into ribbons or large bite-sized pieces.

Slice the leeks in half lengthwise and trim off the roots and dark green parts. Wash well, then cut into thin crosswise slices.

Finely chop the garlic.

Remove the kernels from the corn cobs.

Heat the oil in a large frying pan over medium heat. Add the leeks and garlic, along with a generous pinch of salt. Cook, stirring frequently, until leeks are softened, 5 to 7 minutes.

Add the chard by the handful as it fits in the pan and cook until wilted.

Add the corn kernels and cook for two minutes more, stirring once or twice.

Remove pan from heat. If there is any accumulated liquid at the bottom, drain it well.

Stir in vinegar.

By now the dough should be soft enough to roll out. Sprinkle a little bit of flour on each side of the dough and then replace the parchment.

Using a rolling pin and turning the dough a quarter-turn clockwise every so often, roll the dough out between the parchment into a 14-inch circle (which should be about the same size as the parchment sheets themselves.

Remove the top sheet of parchment and slide the dough (still on the bottom sheet of parchment) onto a pizza pan or baking sheet.

Brush a little bit of olive oil over the surface of the dough, leaving a 1 ½-inch ring around the outer edge.

Sprinkle all but the outside ring of dough with half the Pecorino cheese and some freshly ground black pepper. Tear the Taleggio into small pieces, rind and all, and dot the surface of the dough with half of them, reserving the other half. Do the same with half the chopped olives.

Spread the chard mixture onto the dough, still leaving an outer ring. Top with the other half of the Taleggio, olives and Pecorino.

Fold the outer ring of dough over the chard mixture in 6 to 8 roughly equal sections, pressing gently at the pleats to stick them together.

In a small bowl, beat the egg with the splash of milk or cream to make an egg wash. Brush the dough with some of the egg wash.

Bake for 40 minutes, rotating the pan halfway through to ensure even cooking. Slice into wedges and serve warm or at room temperature.