2 1/3 C. cake flour or pastry flour
1/3 C. granulated sugar
1/2 lb. unsalted butter, chilled, cut into small pieces
2 egg yolks
1 to 2 Tbs. heavy cream
2 Tbs. unsalted butter
8 large ripe plums, halved, pitted, and cut into slices 1/4 inch thick
1/4 C. granulated sugar
1 Tbs. lemon juice
1 Tbs. plum brandy (optional)
First, make the Sugar Dough: In a food processor fitted with the stainless-steel blade, combine the flour and sugar. Add the butter and process until the texture resembles fine meal. In a small bowl, whisk together the egg yolks and 1 Tbs. of the cream. Scrape into the processor and process until a ball begins to form, drizzling in the additional Tbs. of cream, if necessary, to help the dough come together. Remove the dough from the machine and, on a lightly floured surface, press down into a circle. Wrap in plastic wrap and chill in the refrigerator for at least 1 hour. Before assembling the tart, preheat the oven to 350 degrees.
Remove the Sugar Dough from the refrigerator and unwrap it. On a lightly floured surface, use a rolling pin to roll out the dough to a rough circle 14 inches in diameter. Lift up the dough and transfer it to a nonstick baking sheet. Put the baking sheet in the refrigerator while you prepare the plums. In a large sauté pan over medium heat, melt the butter. Add the plums and sauté just until they begin to soften slightly, about 3 minutes. Gently stir in the sugar and lemon juice.
Remove from the heat and, if you like, drizzle in the plum brandy. Let the mixture cool to room temperature. Remove the dough from the refrigerator. Spoon the cooled plums into the center of the dough, spreading them evenly and leaving a 2-inch border all around the edge. Fold the edge up over the plums, leaving the fruit in the center of the tart exposed. In a small bowl, lightly beat the egg. Brush the exposed rim of dough with the egg. Bake until the crust is golden brown, about 30 minutes. Remove from the oven and sprinkle with powdered sugar. Serve warm or at room temperature, cut into wedges.