Preheat the oven to 425 degrees. Spray a 9x13 baking dish with cooking spray and set aside.
In a pyrex measuring cup add 2 cups water and 2 chicken bouillon cubes. Microwave on high fortwo minutes. Set aside.
In a large skillet over medium heat add olive oil and onion. Cook for 5-7 minutes, or until the onion is soft and translucent. Add minced garlic and cook for 1-2 additional minutes. Turn off heat and add shredded cooked chicken, salt, and pepper. Stir to combine. Set aside.
Assemble the tortillas by splitting the mixture evenly between 8 tortillas. Divide 2 cups of monterey jack cheese and evenly top each of the chicken mixture in the 8 tortillas. Roll tightly and place the seam side down in the baking dish. Set aside.
In a saucepan over medium heat add butter and allow to melt. Once melted add flour and whisk together.
Add chicken broth and whisk until smooth and creamy, about 5 minutes. Stir constantly while cooking so it doesn’t burn to the bottom of the saucepan.
Mix in the sour cream, salt, pepper, green chilies, and monterey jack cheese.
Pour the white sauce over the top of the enchiladas. Top with 1 cup shredded mexican blend cheese.
Bake at 425 for 20 minutes, or until the cheese is fully melted and barely starting to brown.