Heat a sturdy cast iron pan or griddle over medium-high heat. When the griddle is hot, place 1 tortilla on the griddle and sprinkle 1/8 of the cheese on tortilla. Top with 1/4 of the chicken mixture, 1/4 of the avocado, 1/4 of the green chiles, and 1/4 of the cilantro, and another 1/8 of the cheese. Top with another tortilla. When cheese begins to melt, flip with wide spatula and continue cooking until cheese is melted. Remove from griddle to cutting board. Cut into 4 pieces. Repeat process 3 more times. Serve with fat-free sour cream on the side.