Preparation

• Position a rack in the center of the oven and heat the oven to 400°F. Let the dough sit at room temperature until pliable, 10 to 15 minutes.
• Meanwhile, heat the oil in a 12-inch skillet over medium heat. Add the onion and cook, stirring, until softened, about 3 minutes. Add the chard and cook until tender, 3 to 4 minutes.Remove the skillet from the heat, and stir in the corn, garlic, chile, 1/2 tsp. kosher salt, and a pinch pepper. Transfer to a large plate or rimmed baking sheet to cool, then toss with 1 Tbs. of the mint.
• In a small bowl, whisk the whole egg and cream. In a large bowl, combine the ricotta, Parmigiano, the remaining 1 Tbs. mint, the egg yolk, 1/2 tsp. kosher salt, and a pinch pepper. Reserve 1/4 cup of the cheese mixture. Gently mix the remaining cheese mixture with the Swiss chard mixture.
• Roll the dough between 2 sheets of lightly floured parchment paper into a 14-inch round, loosening the parchment from the dough occasionally and adding a bit more flour if it sticks. Transfer on the parchment to a baking sheet; remove and discard the top sheet of parchment.
• Leaving a 2-inch border, spread the chard mixture over the dough, then dollop with the reserved cheese mixture.
• Fold the edge of the dough up and over the filling. If the dough is sticking to the parchment, refrigerate it for 5 to 10 minutes, and then continue folding. Brush the folded dough with the egg wash.
• Bake, rotating the baking sheet once halfway through, until the crust is golden brown, 40 to 50 minutes. Transfer to a cooling rack, season generously with flaky sea salt, and let cool for 10 to 15 minutes. Serve warm or at room temperature.