Mix Dry Ingredients: Add almond flour, coconut flour, xanthan gum, baking powder, and salt to a food processor. Pulse until evenly combined.
Add Wet Ingredients: Add in the egg and apple cider vinegar. Pulse until the dough just begins to come together. The mixture should resemble coarse breadcrumbs.
Form Dough: Turn out the dough onto cling film (plastic wrap) and pat into a round disk. Wrap tightly and refrigerate for at least one hour. Alternatively, you can freeze the dough and thaw it as needed.
Roll Out Dough: Roll out the crust between parchment paper. If the dough becomes unmanageable, chill it in the freezer for 5-10 minutes.
Pre-Bake Crust: Once shaped, place the crust in the freezer for 10-15 minutes before baking to help it keep its shape. Brush with egg wash for a glossy finish (optional). Bake at 390°F (200°C) for 8-10 minutes, or until lightly browned.