Combine the almond flour, coconut flour, xanthan gum, and shredded cheese in a large bowl and mix well to combine.
Incorporate the butter into the flour mixture using a fork or pastry cutter.
Add the egg white to the mixture, reserving the yolk for the filling, and mix to form one large dough ball. Place in the refrigerator for 30 minutes to chill.
Preheat your oven to 350F. Press the chilled dough into a pie pan, going to the outer edge and up the sides. This part doesn’t have to be perfect.
Bake the crust for 10 minutes at 350F. Set aside to cool.
Create the filling by whisking the eggs and the remaining egg yolk with heavy cream and salt.
Sautee the asparagus and sliced shallot just until the onion is translucent and the asparagus begins to soften.
Place the cubed gruyere in the bottom of the cooled quiche crust.
Top the cheese with the onion and asparagus.
Pour the egg mixture into the quiche crust and bake at 350F for 45-60 minutes or until it is completely set and slightly browning. Slice and serve!