Preparation

• Put the tomatoes in a colander in the sink or over a bowl, and toss with 1-1/2 tsp. salt. Let drain for at least 45 minutes to release excess juice. Heat the oil in a 12-inch skillet over medium heat. Add the leeks, 1/4 tsp. salt, and 1/4 tsp. pepper; spread in an even layer, reduce the heat to low, and cook, covered, without stirring until the leeks begin to soften, about 5 minutes. Uncover and cook, stirring occasionally, until very tender, 10 to 15 minutes more. Transfer to a plate and let cool completely.
• Meanwhile, 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.
• In a small bowl, whisk the egg and cream.
• 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, sprinkle half of the cheese, half of the leeks, half of the tomatoes, 1 tsp. of the marjoram, 1/4 tsp. of the pepper, and a generous pinch flaky sea salt over the dough. Repeat with remaining ingredients.
• 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 half-way through, until the crust is golden brown, 40 to 50 minutes. Let cool on a rack for 10 to 15 minutes. Serve warm or at room temperature.