Make the Cookie Tart Dough

See recipe.

Chill the Dough

Flatten the dough into a 6 inch disc. Wrap it well and refrigerate it for 30 minutes, or until firm enough to roll or pat into the pan. It can be refrigerated for up to 3 days or frozen for up to 6 months. If chilled for more than 30 minutes, it can take as long as 40 minutes at room temperature to become malleable enough to roll.

Roll the Dough

Set the dough between lightly floured large sheets of plastic wrap. Roll it evenly into a ⅛ inch thick disc larger than 12 inches in diameter. While rolling the dough, sprinkle it with a little more flour on each side as needed and if the dough softens significantly, slip it onto a baking sheet and refrigerate it until firm (see Notes). From time to time, flip the dough with the plastic wrap and lift off and flatten out the plastic wrap as necessary to make sure it does not wrinkle into the dough.

Line the Tart Pan

Remove the top sheet of plastic wrap and use the expandable flan ring, or a pizza wheel or small sharp knife with the cardboard template as a guide, to cut a 12 inch disc. If using the pizza wheel or knife, take care not to cut through the bottom plastic wrap. (Excess dough can be frozen for several months.) If the dough softens after cutting, refrigerate it until firm. It will not drape over the pan unless it is flexible, so if it becomes too rigid in the refrigerator, let it sit and soften for a few minutes.

Invert the 8 inch cake pan onto a work surface. Use the bottom sheet of plastic wrap to lift the dough and set it, plastic side down, over the 8 inch cake pan (see Lemon and Cranberry Tart Tart). Smooth down the sides so they will fit into the tart pan and place the removable bottom of the tart pan on top. Then carefully place the fluted ring, upside down, on top. Place a flat plate, cardboard round, or wire rack over the tart pan to keep it from separating. Invert the pans and remove the cake pan. Carefully peel off the plastic wrap. Gently ease the dough down to reach the bottom and sides of the pan. If the dough breaks when transferring it into the pan, patch and press it into the pan with your fingers.

Fold in the excess dough to halfway down the sides of the tart pan. Press it against the sides so that it extends ⅛ to ¼ inch above the top of the pan. If the dough is thicker in places, press it so that it becomes thinner (it will rise higher). Use small sharp kitchen scissors to trim it to ⅛ to ¼ inch above the top of the pan. If pressing in the dough with your fingers, press it at the juncture where the bottom meets the sides, which often tends to be thicker. For a decorative border, use the back of a knife to make diagonal marks all around, using each flute as a guide.

Chill the Tart Shell

Cover with plastic wrap and refrigerate it or freeze it for a minimum of 1 hour.

Preheat the Oven

Thirty minutes or longer before baking, set oven racks at the middle and lowest levels and preheat the oven to 425°F/220°C.

Bake the Tart Shell

Run a finger along the outside fluted edge of the pan to make sure that no dough is attached. The dough must not extend onto the outside of the pan or as the sides slip down a bit on baking, it will make a hole when the baked crust is removed.

Line the pan with the coffee filter or parchment and fill it three-quarters full with beans or rice to weight it, pushing the weights up against the sides. Carefully transfer the tart pan to the foil-lined baking sheet and set the tart on the lower rack.

Bake for 5 minutes, lower the heat to 375°F/190°C, and bake for 15 to 20 minutes, or until set. If not set, the dough will stick more to the filter. Lift out the filter with the weights, and continue baking for 5 to 10 minutes more. If the dough starts to puff in places, press it down quickly with your fingertips or the back of a spoon (see Notes). Bake until pale gold (the edges will be a deeper brown) and the tart shell feels set but still soft to the touch. (It will continue firming while cooling, just the way cookies do.)

Cool the Tart Shell

Remove the tart pan, still on the baking sheet, to a wire rack. If any holes have formed, seal them with a little egg white and return the pan to the oven for 30 seconds for the egg white to set and become opaque. Alternatively, seal the hole or holes with a little melted white chocolate.

Let the tart shell cool for 3 minutes and then brush the bottom and sides to coat well with some of the reserved egg white, lightly beaten, to moisture-proof the crust. Cool completely.

Lower the oven temperature to 350°F/175°C.

The unbaked tart shell can be refrigerated for 1 week or frozen for about 1 year. The baked tart shell without the brushed egg white will keep at room temperature in an airtight container for 2 days.

Make the Lemon Cream Filling

See recipe.

Bake the Tart

Set the tart shell, still on the foil-lined baking sheet, on the middle rack of the oven and carefully pour in the filling. It will fill the tart shell to the top. If your tart crust has shrunk or lowered in the pan, there will be some extra filling. Lower the heat to 325°F/160°C and bake for 20 minutes. Carefully turn the tart halfway around, lower the heat to 300°F/150°C, and continue baking for 15 minutes. Turn off the oven and let the tart sit for 5 to 15 minutes. When moved, the center should jiggle very slightly. (An instant-read thermometer should read about 170°F/77°C.)

Cool the Tart

Avoid touching the filling’s surface because it will tear and stick to your finger. Use a cake lifter or 10 inch or longer grill spatula to slide the tart onto a wire rack to cool completely, about 45 minutes.