When measuring flour, we spoon it into a dry measuring cup and level off the excess. (Scooping directly from the bag compacts the flour, resulting in dry baked goods.) To make the dough in a food processor: Pulse the flour, sugar and salt in a food processor until combined. Add the butter and pulse until it resembles coarse cornmeal mixed with pea-sized bits of butter, about 10 times. Add the egg and water mixture and pulse 1 to 2 times (do not let the dough form into a ball in the machine). If the dough is very dry, add up to 1 tablespoon more of cold water. Turn the flour mixture out of the machine onto a work surface and bring the dough together by hand.