Rinse and clean 1 whole chicken and put in stockpot with seasonings,onion and garlic. Cover with water then cover pot and cook for 30 mins. to an hour, depending on size of chicken
Once chicken is done and falling off the bone. Slowly remove the chicken from the pot and put on a cutting board or dish for shredding. Using two forks, shred the chicken and remove all the bones and skin. Set aside the shredded chicken
Strain the broth in the pot over a heat resistant bowl. Let cool slightly before using. You can store the remaining broth or toss it out
In a large bowl, mix enchilada sauce, sour cream and broth together. Add chilies and chicken.
Take the two tablespoons of enchilada sauce that was set aside and spread over the base of the casserole dish or pyrex dish (9x13). Lay down 4 tortillas, then cover with the chicken mixture and sprinkle some cheese on top. Repeat layers until dish is full. You should end with a layer of tortillas, 2 tablespoons enchilada sauce and cheese
Cover with foil and bake for 30 minutes at 350-degrees. Remove foil and bake for 15 mins. longer or until nice and brown on top