Add the almond flour, coconut flour, salt, xanthan gum, and vinegar into a food processor. Pulse a few times, then add the cold butter. Continue pulsing until the pie dough looks like bread crumbs. Add the egg to the food processor and pulse again. The dough will be able to be formed into a ball. Wrap with plastic wrap and chill for 45-60 minutes.

Preheat the oven to 350F. Grease a baking dish that will fit your quiche and a piece of foil with nonstick spray then set aside.

When the dough is chilled, place it between two sheets of parchment paper. Roll the dough out into a circle that will fit your baking dish. (More circles if you are making more than one pie or have a small baking dish.) Peel the top layer of parchment off and flip the dough into the pie plate if the dough breaks mash it back together with your fingers.

Layer half of the mozzarella and pepperoni inside the pie crust. In a mixing bowl whisk the eggs, heavy cream, Italian seasoning, red pepper flakes, salt, and pepper together.

Pour the eggs into the pie crust, coating the pepperoni and cheese. Sprinkle the top with the remaining cheese and pepperoni.

Cover with foil then bake for about 35-45 minutes. Remove the foil and continue baking for another 10-15 minutes or until the eggs are fully set.