Preheat oven to 350°F. Cook chicken breast (either pan fry or bake). Use a fork to shred the chicken. In a large bowl mix shredded chicken with fajita seasoning. Next add cheddar cheese soup and green chilies.
Add 1/2 can of enchilada sauce to the bottom of a 13 x 9 pan. Warm tortilla shells in the microwave for 30 seconds under a damp paper towel. Spoon chicken mixture into the center of each tortilla. Fold the ends in first, then wrap, placing in the pan seam side down. Place the enchiladas in a row inside the pan. Spoon enchilada sauce down the middle of the row over the enchiladas. Top with cheese.