Start by preheating your oven to 350 degrees.
Spray a 9x13 baking dish with non-stick cooking spray and set aside.
In a large bowl, whisk the cream of chicken soup, cream of mushroom soup, sour cream, and diced green chiles together. Set aside.
In a small saucepan on the stove, over medium heat, melt the butter to a sizzle.
Add the green onions and garlic.
Lightly sauté' and add to the sauce mixture in the bowl. Mix well.
Spoon 1 cup of the sauce into a medium bowl and whisk in the milk. Set this aside.
Add the cooked and chopped-up chicken and 1 cup of shredded cheese to the remaining sauce in the large bowl.
Mix well.
Lay 8 tortillas out across your countertop.
Divide the chicken filling among all the tortillas, spooning the filling down the center of each tortilla.
Roll up and place seam side down in the prepared baking dish.
Pour the remaining white sauce that you whisked the milk into over the tops of the enchiladas.
Sprinkled the remaining cheese on top.
Bake at 350 degrees for 30-40 minutes.
Cool slightly before serving.