Chicken Enchiladas with Sour Cream Sauce

Pre-heat the oven to 350° F, and lightly grease a 9x13 baking dish with cooking spray.
Combine the picante sauce and shredded chicken in a container, and let it marinate in the fridge while you're making the enchilada sauce.
Melt the butter in a medium sauce pan over low to medium heat.
Sauté the onion in the butter until it turns a light golden color, about 5 minutes or so.
Add the cream cheese to the onion, stirring well until it melts.
Then add the sour cream, heavy whipping cream, green chilies, salt, pepper, 1/2 cup cheddar, and 1/2 cup Monterey Jack to the sauce mixture.
Let the sauce simmer, constantly stirring, until it begins to thicken up, probably 10 to 15 minutes.
Stir 1 cup of the freshly diced tomatoes into the sauce. Turn the burner on low and keep the sauce warm at this point.
Add a heaping tablespoon of the marinated chicken to each corn tortilla, and loosely wrap each enchilada.
Place each chicken enchilada in the prepared baking dish.
When all of the chicken mixture has been used, pour the white sour cream sauce over the wraps, spreading it around evenly.
Add another cup of freshly diced tomatoes, as well as the rest of the cheese and the green onions, to the top of the enchiladas.
Bake at 350° F for about 40-45 minutes, or until the cheese is melted and the enchiladas are cooked through.
Serve with freshly diced tomatoes, avocado, and sour cream on the side.