Preheat the oven to 350 degrees F (175 degrees F).
In a large bowl, stir together the Cheddar cheese soup, half-and-half, cream cheese, onion flakes, garlic powder, mustard powder, chicken bouillon granules, salt and pepper. It will be slightly lumpy.
Grease a 9x13 inch baking dish, and layer 1/3 of the potato slices over the bottom so that they overlap slightly. Sprinkle half of the garlic and celery over this layer. Repeat layers ending with potatoes on top. Pour the cheese soup mixture evenly over the whole dish. Cover tightly with aluminum foil.
Bake for 45 minutes in the preheated oven. Remove from the oven, and sprinkle Cheddar and Parmesan cheeses over the top. Return to the oven uncovered, and bake for 20 more minutes, or until a butter knife can easily be inserted into the potatoes.