Combine almond flour, coconut flour, and sea salt in mixing bowl.
Add beaten egg, melted butter, and maple syrup. Mix with spoon until combined.
Press into greased 8x8 square pan. I use two pieces of parchment paper which I cross and put on top of the greased pan. This allows the paper to stick and makes for easy removal!
Use a fork to pierce the crust in a few places
Bake in the oven at 350 degrees for about 15 minutes, or until cooked through and edges are starting to brown. Don't overcook as it will bake more with the lemon filling.
Lemon filling
While crust is baking, prepare lemon filling.
Combine eggs, egg yolk, and sugar. Beat on medium speed until mixture is a light yellow color, about 2-3 minutes.
Mix in lemon juice, lemon zest, and vanilla.
Sprinkle baking powder and gluten free flour on top, then mix gently until blended.
Pour lemon mixture over hot shortbread, then return to oven and bake 18-20 minutes. Top will be crackly and fairly set, but will thicken even more while cooling.
Let cool on wire rack completely.
For optimal consistency and slicing, refrigerate for at least two hours but preferably overnight. Cut with a sharpened knife and wipe blade in between slices.
Top with sifted powdered sugar before serving.
Keyword Cookie Recipe, gluten free dessert, lemon bar, lemon dessert