Preheat oven to 400°. Pat chicken dry with paper towels; season with salt and cumin.

Heat oil in a 12-inch cast iron skillet over medium heat. Add chicken; cook 3 to 4 minutes or until chicken reaches 165°, stirring frequently. Transfer chicken to a medium bowl; set aside.

Add water to same skillet. Cook, scraping and stirring browned bits from bottom of skillet. Pour water mixture over chicken in bowl. Wipe skillet dry with paper towel. Spray with nonstick spray; set aside.

Stir together egg, corn muffin mix, milk, and taco seasoning in a large bowl just until moistened. Stir in corn and green chiles just until combined. Spread evenly in prepared skillet. Bake 30 minutes or until toothpick inserted near center comes out clean. Meanwhile, shred chicken in bowl using 2 forks.

Pierce top of corn bread several times with tines of fork. Layer with ½ cup Monterey Jack cheese, enchilada sauce, shredded chicken mixture, and remaining 1 cup Monterey Jack cheese/ Bake 12 to 15 minutes or until heated through (165°). Let stand 5 minutes before serving. Garnish with tomato, Cotija cheese, and cilantro, if desired.