Step 1

Preheat the oven to 350ºF degrees. Line a 9-inch square pan with parchment paper with enough overhang easy removal.

Step 2

In a medium bowl, combine the flour, sugar, salt, and lemon zest. Stir to combine. Using a pastry blender or your fingertips, cut in the butter until the mixture begins to hold together.

Step 3

Press the dough evenly into the bottom of the prepared pan. If the dough is too sticky to handle moisten your fingers with water to prevent sticking or pop the dough into the refrigerator for 15 minutes.

Step 4

Bake for 15 to 20 minutes, or until lightly golden brown. Set aside while you make the filling.

Step 5

Whisk the eggs, yolks, sugar, and salt together in a medium pot. Stir in the lemon juice.

Step 6

Cook over medium heat, stirring constantly, for about 10 minutes. The curd will thicken to the consistency of pudding.

Step 7

Stir the butter and cream into the smooth curd filling.

Step 8

Strain the curd through a fine-mesh sieve set over a medium bowl.

Step 9

Pour the curd over the crust and spread evenly with a silicone spatula. Bake for 20 to 25 minutes, or until the filling is set. The edges should be firm and the center should no longer jiggle.

Step 10

Remove from the oven and cool on a wire rack for 1 hour. Cover and refrigerate for at least 2 hours.

Step 11

Lift the bars out of the pan using the parchment overhang and cut into 16 squares. Dust with powdered sugar if desired.