Lemon Triangles

Preheat the oven to 350°. Lightly butter a 13 x 9 inch baking sheet and line with parchment paper, allowing the paper to come up the sides of the pan.

Pulse the flour, powdered sugar, cornstarch and salt in a food processor. Slice the butter into 1-inch pieces. Add the butter to the processor and process to blend, about 8 to 10 seconds, and then pulse until the mixture is pale yellow and resembles coarse meal, about three 1-second bursts. Sprinkle the mixture into the lined pan and press firmly with your fingers to form an even, 1/4-inch layer over the entire pan bottom. Refrigerate for 30 minutes, and bake for about 20-25 minutes, until golden brown.

Meanwhile, whisk together the eggs, sugar, lemon zest, lemon juice and flour. Pour over the warm crust and bake for 30 to 35 minutes, until the filling is set. Let cool to room temperature (or refrigerate overnight in the pan). Using the parchment to pull it out of the pan, transfer to a cutting board and peel the paper down. Using a sharp knife or pizza cutter, cut into 20 squares. Then cut each square diagonally to form 40 triangles. Sprinkle with powdered sugar before serving.