For baking: 1 egg, beaten For dough, in a large mixing bowl, mix dry ingredients. Add 1/4 pound soft butter and work finely into flour. Cut cold butter into 1/2 pieces and add to bowl. Work in until butter is left pea-sized. Drizzle water over mixture and toss in. If dough is dry, add more water, 1 tablespoon at a time, as needed. Dough should be loose in bowl, not in a ball. Turn out onto work surface and pull together. Divide into 2 equal portions, flatten each slightly, and wrap in plastic. Chill at least 1 hour before rolling. (Refrigerate up to 3 days, freeze up to 6 months.) For the fig filling, in a large saucepan, combine all but 1/3 of the grated zest and butter, and bring to a boil over medium heat, stirring frequently to dissolve the sugar. Reduce heat and simmer for 30 to 40 minutes until fruit is soft and liquid thickened. Transfer to a food processor and puree until smooth. Add butter and puree to blend. Add remaining zest and pulse in. Transfer to a bowl and allow to cool. To assemble and bake, preheat oven to 375 degrees. Line a 11 by 17-inch baking sheet (up to 12 x18) with parchment paper. Remove one of the wrapped pieces of dough from the refrigerator and unwrap. Roll dough on a floured surface into a rectangle to fit the bottom and sides of the baking sheet. Line the sheet with the dough. Place the baking sheet in the freezer while the second piece of dough is rolled out in the same way. Remove baking sheet from freezer and spread fig filling evenly over the surface of the dough. Top with the second sheet of dough and pinch the edges to seal. Trim the excess dough. Brush surface of dough with beaten egg. Prick through the top layer of dough with a fork evenly over the surface (about 1 1/2 apart.) Place baking sheet on bottom rack of oven. Bake 25 to35 minutes, until dough is a light-medium golden brown. Remove from oven and cool on a wire rack. Cut into portions (squares are traditional.)