Preheat the oven to 350°F (180°C). Line a 9-inch square pan with parchment paper, leaving some paper hanging over the sides. Lightly grease the paper with butter or coconut oil and set aside.

In a mixing bowl, combine almond flour, salt, granulated sweetener, beaten egg, vanilla extract, and melted butter. The mixture should be crumbly, yet hold together when pressed. If it’s too dry, add an extra tablespoon of melted butter.

Press the crumbly shortbread mixture into the prepared pan evenly and firmly. Prick the crust with a fork.

Pre-bake the crust for 15 minutes until golden brown and crispy around the edges.

While the crust is baking, whisk together the eggs, lemon juice, melted butter, granulated sweetener, and lemon zest. Finally, incorporate the almond flour for a smooth consistency.

As soon as the crust comes out of the oven, pour the lemon filling on top.

Return the pan to the oven for another 15-18 minutes, or until the filling is set on top but still soft and jiggly in the center. Keep a close eye to avoid overbaking.

Allow the bars to cool in the pan for 1 hour before transferring them to the fridge to chill for 3 hours or overnight for easier slicing.

Serve chilled, optionally dusted with powdered erythritol and extra lemon zest.