Preheat oven to 350 degrees.

Heat oil in a frying pan over medium heat. Cook onions until lightly browned.

In a large bowl, combine cooked onions, chicken, cilantro, corn, chiles, 1 cup enchilada sauce, ½ of the cheese, garlic, onion powder and chopped chipotles or chipotle powder if desired.

Wrap your stack of tortillas in a large damp paper towel or damp clean kitchen towel. Microwave the tortillas for 60-90 seconds. Just enough to warm them up. The damp towel helps to steam them and keep them from breaking when you fill and roll them.

Create an assembly area with your bowl of chicken mixture, a large (9x13) casserole dish and your wrapped stack of tortillas.

Pour ½ of the remaining enchilada sauce in the bottom of the casserole dish. Now fill each tortilla with a heaping ⅓ cup of filling, rolling it closed and placing it seam side down in the casserole dish until all of the mixture and tortillas are used.

Pour remaining enchilada sauce on top of the tortillas, then sprinkle the remaining cheese evenly on top. Bake for approximately 30 minutes, or until the cheese is melted and slightly browned and it is heated through. Serve with sour cream and a sprinkle of fresh chopped cilantro.