01 - Preheat oven to 350°F. Lightly grease a 9x13-inch baking dish and set aside.
02 - Combine shredded cooked chicken, 1 cup Monterey Jack cheese, 1/2 cup sour cream, green onions, garlic powder, ground cumin, salt, and black pepper in a large mixing bowl. Mix until well blended.
03 - Melt unsalted butter in a saucepan over medium heat. Add all-purpose flour and stir for 1 to 2 minutes until the mixture is bubbling but not brown.
04 - Gradually whisk in chicken broth. Continue stirring until the sauce thickens slightly, about 3 minutes.
05 - Remove saucepan from heat. Whisk in 1 cup sour cream, diced green chilies, onion powder, and salt until smooth.
06 - Evenly distribute chicken filling among flour tortillas. Roll each tightly and arrange seam side down in the prepared baking dish.
07 - Pour the white sauce evenly over the tortillas in the dish. Sprinkle the remaining 1 cup of Monterey Jack cheese over the top.
08 - Bake uncovered for 25 to 30 minutes until the cheese is melted, the sauce is bubbling, and the top is lightly golden.
09 - Allow the dish to rest briefly after baking. Garnish with chopped cilantro and extra green onions before serving.