Sour Cream Chicken Enchiladas

2 cups cooked chicken (with skin and bones removed, diced or shredded, about one pound) 
8 flour or corn tortillas (8 -10 inches wide) 
1 tablespoon olive oil 
1 medium onion, chopped fine 
2 garlic cloves, minced
1 teaspoon ground cumin 
1 teaspoon chili powder 
2 cups shredded Mexican blend cheese (divided, can also use a Monterey Jack and Cheddar blend, or an Italian blend)

Sour Cream Enchilada Sauce:

1⁄ 4 cup unsalted butter 
1⁄ 4 cup all-purpose flour 
1⁄ 2 teaspoon kosher salt 
1⁄ 4 teaspoon ground black pepper 
2 cups reduced-sodium chicken stock 
1 cup sour cream.
1⁄ 2 cup diced tomatoes and green chilies drained (about 1⁄ 2 of a 10 oz can of Rotel) 

To make sauce, melt the butter in a medium-size skillet or saucepan over medium heat. Add the flour, salt, and pepper, and whisk to combine. Stir and cook for one to two minutes or until the mixture is bubbly and just starting to change color.  Slowly pour in the chicken stock and constantly whisk to eliminate any lumps. Bring to a boil and cook for three to four minutes more until the mixture thickens.  Remove the white sauce from the heat and add the sour cream, and diced tomatoes and green chilies. Mix well. 

Preheat the oven to 400 degrees F.  In frying pan pan, sauté onion in olive oil until tender and translucent.   Add the garlic and cook for about 30 seconds.  Add the chicken, cumin, and chili powder, stir to combine, and cook for one to two minutes or until everything is heated. Remove from the heat and allow to cool briefly. Add one and one-half cups of cheese and stir to combine.

Place about one-third of a cup of the mixture in the middle of each tortilla and roll up tightly. Place the enchiladas seam side down in a 9×13 oven-safe baking dish, sprayed with non-stick cooking spray.   Pour the sour cream sauce evenly over the enchiladas and sprinkle the remaining cheese over the top.  Bake for 20-25 minutes until the cheese is melted and the sauce is bubbly.

Serve immediately with your favorite toppings such as sour cream, salsa or pico de Gallo, sliced avocado or guacamole, and extra grated cheddar cheese.  Makes 8 enchiladas. 
To make ahead, cover the unbaked enchiladas and store them in the refrigerator for up to 24 hours or wrap tightly with foil and place them in the freezer for up to 3 months. If refrigerated, take the casserole out approximately one hour before baking to come to room temperature. If frozen, allow it to thaw overnight in the refrigerator before baking.