01 - Preheat the oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish.
02 - In a large mixing bowl, combine the shredded chicken, 1 cup Monterey Jack cheese, 1/2 cup sour cream, green onions, garlic powder, ground cumin, 1/4 teaspoon salt, and black pepper. Mix thoroughly until evenly incorporated.
03 - In a saucepan over medium heat, melt the butter. Stir in the all-purpose flour and cook for 1 to 2 minutes, stirring constantly, until the mixture is bubbling but does not brown.
04 - Gradually whisk in the chicken broth. Continue to cook, stirring, until the sauce is slightly thickened, about 3 minutes.
05 - Remove saucepan from heat. Whisk in 1 cup sour cream, diced green chilies, onion powder, and 1/2 teaspoon salt until the sauce is smooth and homogeneous.
06 - Distribute the chicken filling evenly onto each flour tortilla. Roll the tortillas tightly and arrange them seam-side down in the prepared baking dish.
07 - Pour the white sauce evenly over the arranged enchiladas. Sprinkle the remaining 1 cup Monterey Jack cheese over the top.
08 - Bake uncovered for 25 to 30 minutes, or until the enchiladas are bubbling and lightly golden on top.
09 - Allow to cool briefly. Garnish with chopped cilantro and additional green onions before serving.