Preheat your oven to 350°F (175°C) and line an 8x8-inch baking pan with parchment paper.

In a large mixing bowl, combine all-purpose flour, granulated sugar, and a pinch of salt. Cut in the cold unsalted butter until the mixture resembles coarse crumbs. Stir in the vanilla extract.

Press about two-thirds of the crumb mixture into the bottom of your prepared baking pan.

Par-bake the crust for 15 minutes or until lightly golden.

In a medium bowl, whisk together the eggs and granulated sugar until smooth. Add flour, lemon zest, lemon juice, and salt, mixing until combined.

Pour the lemon filling over the warm crust and spread it evenly.

Sprinkle the reserved crumble mixture over the top of the lemon filling.

Bake for 20-23 minutes until the filling is set and the topping is golden brown.

Let the bars cool in the pan for about 30 minutes, then chill in the refrigerator for at least 1 hour.

Lift the bars from the pan using the parchment overhang and slice into squares.