Pour 1 cup of ammonia into a large shallow bowl. Expose as much surface area of the ammonia as possible to the air.
Place the bowl of ammonia in the middle of a cold oven on the lowest rack.
Leave the bowl of ammonia in the closed oven overnight, or approximately eight to 10 hours.
Take the bowl of ammonia out of the oven and pour it into a 1 gallon tub of lukewarm water.
Remove the racks from the oven. Scrape off food deposits between the narrow grills of the oven racks with the dull edge of a butter knife. Use the ammonia solution and a nylon scrub pad to finish cleaning the racks.
Remove the oven door by opening it approximately one quarter of the way, lift up and pull the oven door off its hinges. Set the door aside.
Scrape off hardened food deposits in the oven with a wooden spoon.
Scrub the food deposit residue in the oven with the ammonia solution and a nylon scrub pad.
Clean the inside walls of the oven and the oven door with the ammonia solution and scrub pad.
Rinse the inside of the oven and the door thoroughly with a clean cloth soaked with water. Remove all food residue, and all traces of ammonia.
Replace the oven racks and the oven door.