In a large bowl, combine all cheeses, cooked chicken, sour cream, soup, onion, salt and pepper. Spoon about 1/2 cup of this mixture off center on each tortilla; roll up. Place seam side down in a greased 13x9x2 inch baking dish.
Pour enchilada sauce over the tortillas. Cover with tinfoil and bake at 350 degrees F for approximately 45 minutes. Let stand for 10 minutes before serving.