01 - Preheat the oven to 350°F (175°C) and lightly grease a 9x13-inch baking dish.
02 - In a large mixing bowl, combine shredded chicken, Monterey Jack cheese, sour cream, green onions, garlic powder, ground cumin, salt, and black pepper until evenly blended.
03 - In a saucepan over medium heat, melt unsalted butter. Stir in all-purpose flour and cook, stirring, for 1 to 2 minutes until bubbling but not browned.
04 - Gradually whisk in chicken broth and cook, stirring constantly, until the mixture thickens slightly, about 3 minutes. Remove from heat and whisk in sour cream, diced green chilies, onion powder, and salt until smooth.
05 - Divide the chicken mixture evenly among the flour tortillas. Roll each tortilla tightly and arrange seam-side down in the prepared baking dish.
06 - Pour the white sauce evenly over the filled tortillas and sprinkle with the remaining Monterey Jack cheese.
07 - Bake uncovered for 25 to 30 minutes, until the top is bubbly and lightly golden.
08 - Let rest briefly out of the oven, then garnish with chopped cilantro and additional green onions before serving.