Place the chicken breast, chicken thighs and tomato sauce in the slow cooker. Sprinkle the seasoning and salt and pepper over the top. Set on low and cook for 8 hours.
Once cooked, shred the chicken in the sauce and lightly drain.
Preheat oven to 350.
Place 5 corn tortillas at the base of each 9×13 inch baking dish or disposable baking pan, if freezing. I usually tear one of two of the tortillas to cover as much of the base as you can.
Add 1/2 of the chicken and tomato mixture. Then top with 5 more tortillas. Then repeat with the chicken and tomato mixture and one more layer of tortillas. Top with about 1 to 1 1/4 cup shredded cheese. Repeat in the other baking dish.
Place in the oven for 15-20 minutes, or until the cheese melts.
Prepare the corn as directed.
Serve Chicken Enchilada Casserole with side of corn.
To freeze the other dish: let cool completely, then cover with foil and freeze. To reheat, let thaw in the refrigerator over night and then bake for 40 minutes at 350, or until heated through. Cooking time may vary based on how much it thawed.