Spray the bottom of a nine by 13-inch baking pan with cooking spray. Pour two tablespoons apple juice into bottom of pan. Spread sliced potatoes evenly on the bottom of the pan. Sprinkle generously with salt and then with the diced onion.

Preheat oven to 350 degrees Fahrenheit (180 degrees Celsius). In a small saucepan, heat the two thirds of a cup of apple juice with the chicken soup. Add the potato starch-water combination once it boils. Lower heat and stir constantly until it begins to thicken; pour over potatoes.

Sprinkle with paprika if desired, then the crushed potato chips. Bake covered for one hour. Uncover and bake another 45 minutes.