01 - Preheat oven to 350°F (175°C) and lightly grease a 9x13-inch baking dish.
02 - In a large mixing bowl, blend shredded chicken with 1 cup Monterey Jack cheese, 1/2 cup sour cream, green onions, garlic powder, cumin, salt, and pepper until fully incorporated.
03 - Melt butter in a saucepan over medium heat. Stir in flour and cook for 1 to 2 minutes, whisking constantly, until the mixture is bubbling but not browned.
04 - Gradually pour in chicken broth while whisking. Continue stirring and cook for about 3 minutes, or until the mixture is slightly thickened.
05 - Remove saucepan from heat. Whisk in sour cream, diced green chilies, onion powder, and salt until the sauce is smooth.
06 - Evenly divide the chicken mixture among the tortillas. Roll each tortilla tightly and arrange seam-side down in the prepared baking dish.
07 - Pour the prepared white sauce evenly over rolled tortillas and sprinkle with remaining 1 cup shredded Monterey Jack cheese.
08 - Bake uncovered for 25 to 30 minutes, until the cheese is melted and the edges are lightly golden and bubbly.
09 - Let the enchiladas cool briefly. Garnish generously with chopped cilantro and extra green onions before serving.