For the Crust
1 3/4 cups unbleached all-purpose flour
2/3 cup confectioners’ sugar
1/4 cup cornstarch
1 tablespoon lemon zest
3/4 teaspoon salt
12 tablespoons unsalted butter (1 1/2 sticks), cut into 1-inch pieces, slightly softened plus extra for greasing pan

For Lemon-Ricotta Filling
8 oz (1 cup) fresh whole milk Ricotta, drained
4 large eggs, beaten
1 1/3 cups granulated sugar
3 tablespoons unbleached all-purpose flour
2 tablespoons lemon zest
2/3 cup lemon juice from 3 to 4 large lemons, strained
1/4 teaspoon salt

To make the crust: Adjust oven rack to middle position and heat oven to 350 degrees. Using a pastry brush, lightly butter a 13-by-9-inch baking dish and line with one sheet parchment paper. Butter paper, then lay second sheet crosswise over it. Pulse flour, confectioner’s sugar, cornstarch, lemon zest and salt in food processor. Add butter and process to blend; then pulse until mixture is pale yellow and resembles coarse meal. Sprinkle mixture into lined pan and, press firmly with fingers into even layer over entire pan bottom and about 1/2-inch up sides. Refrigerate for 30 minutes, and then bake until light golden brown, about 20 minutes. To make the filling: Whisk ricotta, eggs, sugar, and flour in medium bowl, then stir in lemon zest, juice, and salt to blend well. Reduce oven temperature to 325 degrees. Stir filling mixture before pouring into warm crust. Bake until filling feels firm when touched lightly, about 30 minutes. Transfer pan to wire rack; cool to room temperature, at least 2 hours. Transfer to cutting board, fold paper down, and cut into bars, wiping knife or pizza cutter clean between cuts. Dust with confectioner’s sugar.

Makes 18, 2-inches squares