Preheat oven to 350 degrees F (175 degrees C). Lightly grease a casserole dish.
Cut the chicken into bite size pieces. Place the chicken and onion into a large nonstick skillet and sprinkle with seasoning salt. Cook over medium heat, stirring occasionally, until chicken juices run clear and onion is transparent, 5 to 10 minutes.
Prepare the egg noodles according to package directions. Combine the chicken and onion mixture, soups, and noodles in the prepared casserole dish and toss to mix together evenly. Crush the crackers in a medium bowl. Stir in the butter and sour cream. Mix thoroughly and spread over the chicken mixture.
Bake in preheated oven until the top is golden brown, about 30 minutes.
