Step 1

Preheat oven to 350°F.

Step 2

Lightly spray a 9x13-inch baking pan with cooking spray. Using a mixer fitted with a paddle attachment, cream the butter and sugar together on medium speed (about 2 minutes) until light in color. Add the lemon zest and mix for a few seconds.

Step 3

Combine the flour and salt in a separate bowl. With the mixer on low, add the flour mixture to the butter until just mixed, about 1 minute. Place the dough onto a well-floured board and gather into a ball and transfer to the baking pan. Using your fingers, evenly press and flatten the dough into the baking pan.

Step 4

Chill the dough for 15 minutes. Bake the crust for 15 to 20 minutes, until very lightly browned. Cool the crust in the baking sheet on a wire rack for about 30 minutes, until the dough is slightly firm. Keep oven heated to 350°F.

Step 5

Put the sugar, cornstarch, and lemon juice in a small saucepan and whisk together. Add raspberries to the saucepan. Cook over medium heat, constantly whisking until the puree has broken down and thickened and has come to a bubble, about 6 minutes. Strain the hot thickened puree, discarding the seeds. Set the strained puree aside, at room temperature until ready to use.

Step 6

To make the filling, whisk together the eggs, sugar, lemon zest, and flour until combined. Gradually add the lemon juice and whisk until combined and pour over the crust. Add about a tablespoon-sized spoonfuls of raspberry puree around the entire surface of the lemon mixture. Quickly drag a toothpick across the surface to create swirls.

Step 7

Carefully transfer to the oven. Bake for 30-35 minutes until the filling is set in the center. Let cool to room temperature.

Step 8

Cut into squares or triangles and dust with confectioners' sugar.