In a mixing bowl, combine cream cheese, onions, 1 1/2 cups Mexican-cheese
blend, garlic, 1/4 teaspoon cumin and cilantro. Stir in chicken; set aside.
In a saucepan, melt butter. Stir in flour until smooth; gradually
add broth. Bring to a boil; cook and stir for 2 minutes or until
thickened. Remove from the heat. Stir in Monterey jack cheese, sour
cream, chiles, thyme, salt, pepper and remaining cumin.
Spread 1/2 cup of the cheese sauce in a greased 13 x 9 x 2-inch
baking dish. Top with six tortilla halves, a third of the chicken
mixture and a fourth of the cheese sauce. Repeat tortilla, chicken
and cheese sauce layers twice. Top with remaining tortillas, cheese
sauce and Mexican cheese.
Cover and bake at 350 degrees F for 30 minutes.
Uncover; bake 10 minutes longer or until heated through.