Crock Pot Chicken Enchilada Casserole

1 T oil
1 small onion (diced)
2 cloves garlic (minced)
3 C cooked chicken (cubed)
3 cans enchilada sauce (10 oz cans)
1/2 tsp salt
1/2 tsp pepper
1/2 tsp cumin
4 C shredded Mexican mix cheese (divided)
10 whole flour tortillas (8-inch)
15 oz can black beans (drained and rinsed)
15 oz can Fiesta Corn (drained)
3.8 oz can sliced black olives

Sauté the onion in one tablespoon oil until translucent. Add the minced garlic to the pan and sauté for one minute longer. Add two cans of enchilada sauce, the cooked chicken, the salt, pepper and cumin to the pan. Simmer the chicken in the sauce for about five minutes then remove from heat. Spray or grease the bottom of a six-quart crock pot with oil. Cover the bottom of the crock pot with about a 1/4 cup of chicken and enchilada sauce. Lay two tortillas over the sauce in the bottom of the crock pot. Layer one cup of the chicken and sauce, 1/4 cup corn, 1/4 cup black beans, some olives and top with 1/2 cup of cheese. Repeat layering three more times or until you run out of the chicken filling. Top last layer with two more tortillas and pour the last can of enchilada sauce over the top. Cook for four hours on low. During the last 30 minutes of cooking time sprinkle the remaining two cups of cheese over the top and cook until the cheese has melted. Serve with sour cream and salsa.