PREHEAT oven to 350 degrees F.
BROWN chicken in oil in a large skillet. Add water, tomatoes, spice, masa flour, and jalapeno and bell pepper packets. To Fix It Mild, omit the cayenne pepper. To Fix It Hot, stir in entire cayenne pepper packet. Bring to a boil. Reduce heat and simmer, uncovered, for 10 minutes. Stir in beans and cilantro if using.
SPRAY a 2-quart baking dish (8 in. X 8 in.) with cooking spray. Arrange 3 tortillas, overlapping, in bottom of pan. Spoon over half the chili and half the cheese. Make one more layer with remaining tortillas, chili, and cheese. Bake, uncovered, for 10 minutes.