Preheat oven to 350 degrees F.
In large sauce pan over low/med heat add all ingredients except for the cheese, olive oil and corn tortillas. Stir so that everything is mixed well .
While its warming up heat the corn tortillas in a small amount of olive oil in small sauce pan over low heat . Spray a casserole pan with cooking spray and tear each corn tortilla into 4-8 individual pieces . Lay half of the tortillas on the bottom of the casserole dish and then layer with sauce, chicken and half of the cheese mixture. Repeat layers except keep the cheese off the very top layer .
Cook in oven for 20 minutes and then top off with the last of the cheese and cook for an additional 5 minutes.
Let it cool for about 5 minutes and then serve.