Mix chicken, taco seasoning, salsa and cheese. Arrange 8 tortillas on baking sheets sprayed with non-stick vegetable spray. Spread chicken mixture onto tortillas. Top with remaining tortillas. Spray tops with non-stick vegetable spray. Bake at 350 degrees for 5 to 10 minutes, until tops are golden. Allow to cool for a few minutes; cut into quarters. Garnish with sour cream and avocado slices.