Grate your fresh cheese and set aside. Warm one cup of chicken stock (reserve 1/2 cup) in a large sauce pan over medium heat. Add the garlic powder and onion powder, and stir to combine. Bring the stock to a simmer.
Reduce heat to low and add the sour cream. You don't want the pot to be too hot when adding the sour cream, or it could curdle. Stir for 2-3 minutes until the sour cream is well combined in the sauce. Let it come back up to a low simmer.
In a small bowl, combine the reserved chicken broth with the cornstarch and whisk until no lumps remain to create a slurry. Slowly pour the slurry into the simmering sauce, stirring constantly for about 2-3 minutes until the sauce has thickened.
When the sauce is thick enough to coat the back of a spoon, stir in the green chilis. Add the cheese, and stir it in until fully melted. If you feel the sauce is too thick, whisk in a little bit more chicken stock or water. Season the sauce with salt to taste.
Use this sauce to make my sour cream chicken enchilada casserole! Or use it to make traditional rolled-up white chicken enchiladas. Just fill flour tortillas (or corn tortillas for a gluten-free option) with cooked shredded chicken breast, black beans, and any other fillings you like, and roll them up. Place seam side down in a large casserole dish. Pour sauce over the top, and bake at 350 degrees F for 20-30 minutes. Oh so easy!!