For Shortbread:
cup (1 sticks) unsalted butter, chilled and cubed
1 cups all-purpose flour
cup confectioners sugar
teaspoon kosher salt
For Date-Walnut Filling:
1 cup pitted medjool dates (about 12 large), chopped
2/3 cup all-purpose flour
2/3 cup light brown sugar
cup chopped walnuts
1 teaspoon finely minced fresh rosemary leaves
teaspoon ground cardamom
teaspoon baking powder
teaspoon kosher salt
2 eggs, lightly beaten
Preheat oven to 350 degrees. In a food processor, pulse together all the ingredients for the shortbread until it just begins to come together in large pieces. Turn the dough out into a 9-by-13-inch baking pan and press it into a single layer covering the bottom of a pan. Smooth the top with a rubber spatula. Bake, rotating the pan halfway through, until golden and firm to the touch, 20 to 25 minutes.
Meanwhile in another bowl, stir together all the filling ingredients except the eggs. Whisk in the eggs. When the shortbread is ready, spread the filling over it, then bake until the filling is set about 20 minutes. Cool in the pan, then cut into bars.
Yield: 20 bars
Source: William Yosses, White House executive pastry chef