Make the crust: In a bowl, combine almond flour, melted butter, erythritol and a pinch of salt until mixture forms crumbly dough. Evenly press mixture into prepared 8x8-inch baking pan.
Bake the base: Transfer pie crust to a 350F (175C) preheated oven and bake it for about 10 minutes or until lightly golden. Take out and cool down a little bit.
Make the filling: In a separate large bowl, whisk together eggs, remaining erythritol, lemon juice, zest and vanilla until completely combined.
Combine and bake: Pour the lemon mixture over the crust in the baked pan and return to oven. Bake 15 minutes, or until the filling is just set, firming slightly.
Cool and chill: Let the dessert cool for 30 minutes, then refrigerate until cold, cut into squares.
