Cut the 2 ounces dough in half, shape each half into a 9 to 10-inch rope with your palms, and flatten the ropes slightly. Place the ropes in the tart shell, one across the other at right angles, so that the shell is divided into 4 equal quadrants. Spoon the raspberry and apricot preserves, pastry cream, and cherries each separately into 1 quadrant. Brush the dough with the egg.
Baking: Heat the oven to 350 degrees F. Bake until light golden, 20 to 25 minutes. Immediately brush the fruit with the glaze. Let cool, to room temperature, on a rack.
Cream the butter and the sugar in a mixer bowl with the paddle until pale and creamy. Add the egg, egg yolk, vanilla, and lemon juice, 1 at a time, mixing thoroughly after each addition. Add the flour and salt and mix until the dough comes together and is consistent but still soft. Be careful not to overmix or the pastry will be tough.
At this point you may pat the dough into place in a buttered tart pan and bake it immediately after chilling. Otherwise, divide it into thirds or halves, depending on the size tart you are planning, or flatten the whole amount into a 4 to 5-inch disk.
Chilling: Wrap the dough with plastic wrap or aluminum foil, and refrigerate at least 1 hour but no longer than 1 day.
Shaping: Let the dough stand at room temperature for 30 to 45 minutes before rolling it out. Knead the dough briefly on a lightly floured surface to loosen it and make it supple enough for shaping. Roll the dough out 1/4 to 3/8 inch thick with a rolling pin and ease the dough into a lightly buttered pan. Trim the edge by running the rolling pin or a dough scraper over the edge of the pan to cut the dough neatly and then tidy the edge with your fingers.
For 1 (9-inch) tart shell, use 9 to 10 ounces (250 to 300 grams) dough and roll into a circle. Line a buttered 9-inch tart pan with the dough.
Storage: Store the remaining unrolled dough, including all scraps which may be used again, in the refrigerator for 1 to 3 days or the freezer up to 1 month. Let frozen dough thaw in the refrigerator for 24 hours before rolling it out.
Resting: Refrigerate the dough-lined pan for 20 to 30 minutes to reduce shrinking when the pastry is baked.
Baking. Heat the oven to 350 degrees F.
For partially baked shells: Line each shell with aluminum foil and fill with dried beans or pie weights. Bake until set, 12 to 15 minutes. Remove the foil and weights and let cool 5 to 10 minutes. Place the tart pan on top of a smaller can, such as a coffee can, and gently release the side of the pan from the baked tart crust. Let cool completely on a rack.
Slowly heat the milk, 1 teaspoon of the sugar, and the lemon zest in the top of a double boiler over simmering water or in a small heavy saucepan over low heat. Meanwhile, whisk the remaining sugar, the egg yolks, and salt in a small bowl until thick but still golden, 2 to 3 minutes. Sift in the flour, a little at a time, whisking briskly to mix thoroughly. Whisk 1/4 cup of the boiling milk mixture. 1 tablespoon at a time, into the egg mixture; then pour the egg mixture into the remaining milk mixture. Cook over medium-high heat, whisking constantly, until thickened, 2 to 3 minutes. As it begins to reach a boil and look lumpy, whisk it vigorously to smooth it. When the cream is as thick as mayonnaise, reduce the heat and whisk or stir for another minute. Remove from the heat and discard the lemon zest. Beat in the vanilla and then the butter, 1 tablespoon at a time. Cool the cream quickly by placing the pan in a bowl of cold water or by spreading the cream out on 2 baking sheets. Smear a little butter on top and cover tightly with plastic wrap so that the cream doesn't develop a skin. Cool completely in the refrigerator. You may want to thin it with 1 or 2 tablespoons milk before using. This pastry cream will keep 4 to 5 days in the refrigerator or in the freezer up to 2 months.
Heat the preserves and water in a small heavy saucepan over moderate heat until the mixture comes to a boil and strain through a sieve. Use the glaze while it is still warm. Any leftover glaze will keep indefinitely in a covered jar; heat again before using.
Recipe courtesy of Carol Field, The Italian Baker, HarperCollins, 1995