01 - Preheat oven to 350°F (175°C) and lightly grease a 9x13-inch baking dish.
02 - In a large mixing bowl, thoroughly combine the shredded chicken, 1 cup Monterey Jack cheese, 1/2 cup sour cream, green onions, garlic powder, ground cumin, salt, and black pepper.
03 - In a medium saucepan, melt butter over medium heat. Add flour and stir constantly for 1 to 2 minutes until the mixture is bubbling but remains pale.
04 - Gradually whisk in the chicken broth, stirring continuously until slightly thickened, about 3 minutes. Remove from heat and whisk in 1 cup sour cream, diced green chilies, onion powder, and salt until smooth.
05 - Evenly divide the chicken mixture among the tortillas. Roll each tortilla tightly and place seam-side down in the prepared baking dish.
06 - Pour the prepared white sauce evenly over the enchiladas. Sprinkle the surface with the remaining 1 cup of shredded Monterey Jack cheese.
07 - Transfer to the oven and bake uncovered for 25 to 30 minutes, until the dish is bubbling and the cheese is lightly golden. Allow to cool briefly.
08 - Garnish with chopped cilantro and extra green onions before serving.