Preheat oven to 375 degrees F. Spray 9x13" pan with cooking spray, and set aside.
In medium skillet, melt butter over medium-high heat. Add green chiles and garlic and cook for 1 minute. Add flour, stirring constantly, and cooking another minute.
Add cumin, salt, and chicken broth and bring to a boil. Lower heat and add sour cream and cilantro, stirring until smooth.
Add green chile mixture and avocados to a blender and puree until smooth.
Add ¾ cup of sauce to bottom of prepared dish. Prepare enchiladas by spreading 1-2 tablespoons of cream sauce along with chicken and cheese in the middle of each tortilla. Roll up tightly and place seam down in pan. Pour all but ½ cup of remaining avocado cream sauce on top of enchiladas then sprinkle with remaining cheese.
Bake in preheated oven for 15-20 minutes, until bubbling. I also put the broiler on for a minute to get the top nice and golden brown. Let sit for a few minutes before serving.
Drizzle rest of avocado cream on top and serve topped with a couple slices of avocado. Enjoy!