Preheat the oven to 400°F. Line a baking sheet with parchment paper.

In a bowl, combine the coconut flour, almond flour, xanthan gum, and sea salt. Add the egg and water and knead the dough until smooth. Divide the dough into 4 balls and on a flat surface, roll them between 2 sheets of parchment.

In a skillet, cook each tortilla over medium heat for about 1 minute on each side. Arrange 2 tortillas on the prepared baking sheet and sprinkle them with half the cheese. Add the chicken, tomato, onion, and jalapeño. Season with sea salt and black pepper. Drizzle with the lime juice and the remaining half of the cheese. Place a tortilla on top.

Repeat with the remaining tortillas.

Bake the quesadillas for 3 to 5 minutes, or until the cheese is melted. Cut the quesadillas into four pieces and serve topped with cilantro, sour cream, or pico de gallo, if using.