In a medium bowl, stir together the chicken (cold is fine), taco sauce, and 1 cup of the cheese.
In the bottom of a 9 x 13 pan, spread 2-3 Tbsp of enchilada sauce around to coat the bottom.
Dollop about 2 Tbsp of chicken mixture onto the middle of a tortilla shell and then roll up the tortilla. Place seam side down into the 9 x 13 pan. Repeat this process with remaining 11 tortillas and line them up in the pan. Go ahead, squeeze ’em in!.
Pour the remaining enchilada sauce over the enchiladas and spread evenly (make sure they are all covered). Sprinkle remaining 1 cup of cheese over the enchiladas.
Cover pan with foil and bake for 10 minutes. Uncover and bake for an additional 5 minutes or until sides are bubbling.
Top with toppings of your choice. I prefer going the simple route with olives and lettuce but tomatoes, sour cream, onions would also be good!