Preheat the oven to 350. Grease a large baking sheet. Line it with parchment paper.

Add the flour and powdered sugar to the bowl of a stand mixer and mix briefly to combine.

Add the cold butter cut into small cubes along with the lemon zest and vanilla extract. Mix on low speed until the butter is worked into the flour and the mixture becomes crumbly.

Press the dough evenly into the prepared pan. Bake for about 10 minutes, or until lightly golden.

While the crust bakes, whisk the eggs in a bowl and slowly add the sugar, whisking continuously.

Whisk in the lemon juice, baking powder, salt, flour, and lemon zest until smooth.

Pour the filling over the warm crust and return the pan to the oven. Bake for 12-15 minutes, or until the filling is set.

Let cool at room temperature for about 1 hour. Dust the top with powdered sugar, then transfer the pan to the refrigerator and chill for 2–3 hours so the lemon layer fully sets.

Cut into squares and enjoy! Store leftovers in an airtight container in the refrigerator.