The first thing to do is to remove any debris from the bottom of the oven. You can vacuum it out or wipe off any burnt, loose litter with a rag. (We didn't do this when cleaning the oven at Gygis, we found it very annoying to get rid of all the loose crumbs).
Then you need to preheat the oven to the lowest temperature. While the oven is preheating, boil a pot of water on the stove.
When the oven is preheated, turn it off. If you have an old gas stove with an indicator light, turn it off. Pour 1 cup ammonia into an oven safe bowl and place it on the top rack of the oven.
Place the pot of boiling water on the bottom shelf and close the door.
Now you just have to wait! The best thing you can do is do nothing. Ammonia takes hours to break down the goo in the oven. We find it easiest to set it up before you go to bed and let time do the work for you.
After it has had time to sit, put the ammonia (don't pour it out!), a pot of water, and remove the oven rack from the oven. Leave the door open for a few minutes.
It's time to get rid of all that nasty stuff and add a little dish soap to the ammonia bowl and a quart of warm water. Wear gloves and use a scrubbing pad.
Dip the pad into the mixture, then use the pad to wipe away softened grease and grime. Start at the top, then clean the sides and finish at the bottom. Too much elbow grease shouldn't be consumed at this point!
You can do it by cleaning the door - and enjoy a gorgeous, clean oven.
This is of course the smelliest method. But as far as "elbow grease" goes, it's the easiest. This method takes the least amount of work and effort. Ammonia turns baked grime into a slippery mess that's easy to wipe off with a sponge