Preheat oven to 350º. In a large bowl, mix chicken, onion, egg and seasonings. Add a good amount of ketchup(I never measure it.)about 3/4 cup. Add ritz crackers. Mix in cheese.
Line a 9x13 baking dish with foil and spray with cooking spray. Shape chicken mixture into loaf shape and place in pan. Spread ketchup all over the top. Cover with foil and bake for 1 hour, removing the foil after 1/2 an hour.