Preheat your oven to 350 degrees F and line a large baking sheet with parchment paper, set aside.
In a large bowl whisk together your almond flour, coconut flour, sugar, salt, and baking soda.
Add in your eggs, vanilla, and butter. Mix until everything is smooth and well combined.
Roll about 2 tbs of dough into a ball and place on your baking sheet, flatten slightly until it is about 1/2 inch thick. Repeat with remaining dough leaving at least 3 inches in between cookies.
Bake for 10-12 minutes or until edges just start to brown. When they are fresh out of the oven, using the back of a tbs measure make a dent in the middle of your cookie for your lemon curd.
While your cookies cool make your lemon curd. Start by completely melting your butter in a medium saucepan over medium heat. Once butter is melted stir in your sugar, vanilla, and lemon juice.
Once all of your sugar is melted, continually whisking, slowly add in one yolk at time while whisking. Continue to whisk until your mix slightly thickens 5-10 minutes.
Pour your lemon curd through a mesh strainer into a bowl and quickly whisk in your xanthan gum and gelatin until smooth. Allow mixture to cool for 5-10 minutes on your counter.
While your lemon curd cools, coat your cooled cookies with powdered sugar.
Carefully and slowly pour your lemon curd into the dent in your cookies and allow to set for 10-15 minutes. Enjoy!