Assemble: arrange 4 tortillas on top of sauce in dish (they will be overlapping), arrange half the chicken evenly over tortillas, sprinkle 1/2 cup cheese over chicken, drizzle 1/3 of the sour cream sauce over cheese. Top with four more tortillas, second half of chicken another 1/2 cup of cheese and another 1/3 of the sauce. Finish with last 4 tortillas, then remaining sauce. Finally sprinkle evenly with last cup of cheese.