01 - Preheat oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish.
02 - In a mixing bowl, combine shredded chicken, 1 cup Monterey Jack cheese, 1/2 cup sour cream, green onions, garlic powder, ground cumin, salt, and black pepper. Mix until evenly incorporated.
03 - Melt unsalted butter in a saucepan over medium heat. Stir in all-purpose flour and cook, stirring constantly, for 1 to 2 minutes until the mixture is bubbling but not browned.
04 - Gradually whisk in chicken broth. Continue to cook, whisking frequently, for approximately 3 minutes until slightly thickened.
05 - Remove the saucepan from heat. Whisk in 1 cup sour cream, diced green chilies, onion powder, and salt until the sauce is smooth and homogenous.
06 - Divide the chicken filling evenly among the flour tortillas. Roll each tortilla tightly and arrange seam-side down in the prepared baking dish.
07 - Pour the white sauce evenly over the filled tortillas. Sprinkle with the remaining 1 cup shredded Monterey Jack cheese.
08 - Bake uncovered for 25 to 30 minutes, or until the sauce is bubbling and the cheese is lightly golden.
09 - Let the enchiladas cool briefly. Garnish with chopped cilantro and extra green onions before serving.