To mix the dough by hand, combine flour, sugar, salt and baking powder in a medium
mixing bowl and stir well to mix. Cut butter into 1 tablespoon pieces and add to dry ingredients. Toss once or twice to coat pieces of butter. Then using your hands or a pastry blender, break the butter into tiny pieces and pinch and squeeze it into the dry ingredients. Occasionally reach down to the bottom of the bowl and mix all the ingredients evenly together. Continue rubbing the butter into the dry ingredients until the mixture resembles a coarse ground corn meal and no large pieces of butter remain visible.
Beat the egg(s) in a small bowl and pour over the flour and butter mixture. Stir in with a fork until the dough begins to hold together, but still appears somewhat dry. Scatter a teaspoon of flour on the work surface and scrape the dough out onto it. Press and knead the dough quickly 3 or 4 times, until it is smooth and uniform.
To mix the dough in the food processor, combine flour, sugar, salt and baking powder in work bowl fitted with metal blade. Pulse 3 times at 1second intervals to mix. Cut butter into 1tablespoon pieces and add to work bowl. Process, pulsing repeatedly at 1second intervals, until the mixture is fine and powdery, resembles a coarse ground cornmeal and no large pieces of butter remain visible, about 15 pulses in all.
Add the egg(s) to the work bowl and pulse ten times or so, until the dough forms a ball.
Scatter a teaspoon of flour on the work surface and scrape the dough out onto it. Press and knead the dough quickly 3 or 4 times, until it is smooth and uniform.
Press the dough into a disk (two equal disks for the larger amount of dough). Sandwich the disk(s) of dough between two pieces of plastic wrap and press it into a 6 inch circle. Refrigerate the dough until firm, or until you are ready to use it, at least 1 hour.
Storage: Keep the dough in the refrigerator up to two days, or freeze it doublewrapped in plastic. Because the dough is thin, it will defrost quickly at room temperature when you intend to use it.
Add 1/2 teaspoon ground cinnamon and 1/4 teaspoon each freshly grated nutmeg and ground cloves to the dry ingredients before mixing in the butter. Double the quantities for the 2 crust recipe.
Add 2 tablespoons sifted non alkalized cocoa powder to the dry ingredients before mixing in the butter. Double the quantities for the 2 crust recipe. If the dough seems dry after adding egg(s), add a teaspoon or two of water, no more.