Preheat oven to 350°F (175°C) and lightly grease a 9x13-inch baking dish.

In a medium saucepan over medium heat, melt butter. Whisk in flour and cook for 1-2 minutes, stirring constantly, until pale golden.

Slowly whisk in chicken broth, stirring continuously until the sauce thickens and begins to bubble, about 3-4 minutes.

Reduce heat to low. Stir in softened cream cheese, sour cream, and diced green chilies with their juices. Mix until completely smooth and creamy with no lumps, about 2-3 minutes.

Add diced onion and minced garlic to the sauce. Cook for 3-4 minutes until onion softens and becomes translucent. Season with cumin, salt, and pepper to taste.

In a large bowl, combine shredded chicken with 1 cup of the prepared white sauce and 1 cup of the shredded cheese. Mix thoroughly.

Warm tortillas wrapped in a damp paper towel in the microwave for 15-20 seconds. Spoon about ¼ cup of chicken mixture down the center of each tortilla, roll tightly, and place seam-side down in the prepared baking dish.

Pour remaining white sauce evenly over the assembled enchiladas. Sprinkle with remaining 1 cup of shredded cheese.

Bake uncovered for 20-25 minutes until cheese is melted, bubbly, and developing golden spots.

Let rest for 5 minutes before serving. Garnish with fresh cilantro if desired.