01 - Preheat oven to 350°F (175°C). Grease a 9x13-inch baking dish with nonstick spray or a light coating of butter.
02 - In a large bowl, mix shredded chicken, 1 cup Monterey Jack cheese, 1/2 cup sour cream, green onions, garlic powder, cumin, salt, and black pepper until thoroughly combined.
03 - In a saucepan over medium heat, melt butter. Stir in flour and cook for 1 to 2 minutes until bubbling and fragrant but not browned.
04 - Gradually whisk in chicken broth until smooth. Continue stirring until the mixture thickens slightly, about 3 minutes. Remove from heat and whisk in 1 cup sour cream, diced green chilies, onion powder, and salt until velvety smooth.
05 - Spoon the chicken filling evenly among the tortillas. Roll each tortilla tightly and place seam-side down in the prepared baking dish.
06 - Pour the white sauce evenly over the arranged tortillas. Sprinkle remaining 1 cup Monterey Jack cheese on top.
07 - Place baking dish uncovered in the oven and bake for 25 to 30 minutes, until enchiladas are bubbly and lightly golden on top.
08 - Allow enchiladas to cool for several minutes. Garnish with chopped cilantro and extra green onions before serving.