- For the dough:
- 3 cups bleached all-purpose flour
- 1 cup sugar
- 2 teaspoons baking powder
- 1/4 teaspoon salt
- 10 tablespoons (1 stick plus 2 tablespoons) cold unsalted butter or pareve margarine, cut into 1/2-inch cubes
- 2 eggs
- 2 egg yolks
- 1 teaspoon vanilla extract
- 6 ounces semisweet chocolate
- Make the dough: In the bowl of a food processor fitted with the metal blade, place the flour, sugar, baking powder, and salt. Pulse several times to combine.
- Add the butter; pulse several more times, then process for a few seconds to form mealy crumbs.
- In a small bowl, beat together the eggs, egg yolks, and vanilla. Pour this egg mixture into the processor; pulse several times to mix it in, then process for about 10 seconds. Stir the mixture up from the bottom with a rubber spatula, then process again until the dough begins to clump together, about 10 seconds more.
- Turn out onto a lightly floured surface and, with floured hands, press dough together, divide in half, form into 2 disks. Wrap each disk with plastic wrap; refrigerate for at least 1 hour or up to 3 days. (The dough may be frozen for up to 4 months.)
- Prepare the filling: In a small saucepan over low heat, melt the chocolate and butter together, stirring until perfectly smooth. Add the salt, vanilla, sugar, eggs, flour, and walnuts; stir until well blended. (Any unused portion of the filling can be frozen for up to 4 months.)
- If baking all the hamantaschen at once, on two baking sheets, position the oven racks in the lower and upper thirds of the oven. If making only one sheet at a time, the rack should be in the center of the oven. Preheat oven to 350°F. Dab the corners of the baking sheets with butter; line them with parchment paper.
- If the dough is coming straight from the refrigerator, let it warm slightly at room temperature (about 20 minutes) so it can be rolled out. On a lightly floured board, roll dough to 3/16 inch thick. With a 3-inch round cookie cutter, cut circles of dough, and place them on the prepared sheets.
- Place about 2 teaspoons of filling in the center of each circle. Brush perimeter of circle with egg wash. Using a dough scraper, lift dough to partially cover the filling, spacing it at one-third intervals, like a tri-cornered hat. Brush the tops of the formed cookies with egg wash.
- Bake 15 to 18 minutes or until the cookies are golden brown. If baking more than one sheet at a time, rotate sheets top to bottom and front to back toward the end of the baking time to ensure even browning.
- Remove from oven; let rest on baking sheets for 2 or 3 minutes. Loosen the cookies with a thin metal spatula; transfer to wire cooling racks.
Notes: Cookies may be stored in an airtight container, layered between strips of waxed paper, for up to 5 days. These cookies stand up well to freezing.