Spray bottom of large saucepan with cooking spray and saute garlic and onion until onions are soft.
Add chicken broth, green chiles, sour cream, salt, cumin black pepper and soup stirring with a whisk.
Bring to a boil, stirring constantly.
Remove from heat.
Spread 1 cup of soup mixture in a 13 x 9-inch baking dish coated with cooking spray.
Arrange 4 tortillas over the top of soup mixture (it doesn't matter if there are some gaps--I end up tearing some in halves and fourths to spread them out with very little overlap or gaps--placing torn sides against flat sides of pan.).
Repeat layers (3 tortilla layers topped with 1/4 of remaining soup mixure, 1 cup chicken and 1/2 cup cheese.