Even the most experienced of cooks can end up with an overflowing pan in the oven, and the ensuing mess is often unsightly and difficult to clean. Harsh chemicals have their place when it comes to keeping the home clean, but in the oven, where food is prepared, it's best to stick to methods that don't require harsh commercial cleaners. Items that you may already have around the house can give you the clean oven you're looking for, without investing in any special cleaners.
Use a strong metal spatula to scrape the majority of the burned grime, grease and spilled food off the bottom of the oven. When used like a paint scraper, the spatula should be able to remove most of the big chunks and spills without applying any cleaner.
Remove the large chunks of burned-on food with a cloth, and dispose of as much as possible.
Sprinkle a liberal amount of baking soda on the bottom of the stove to completely cover the burned areas that remain. Fill a spray bottle with water, and spray the baking soda to thoroughly wet it. Leave the wet baking soda in the oven for several hours or overnight.
Use the metal spatula again to scrape the loosened grime and burned residue from the oven. This should remove most of the grime. Use use clean damp cloths to wipe up the mixture of burned food, baking soda and water.
Repeat as necessary. For ovens that haven't been cleaned in a while or have had several major spills, it may be necessary to repeat the process several times.
Cover the bottom of a baking dish with water. Squeeze 2 lemons into the dish, then slice the peels and place in the dish as well. Bake for at least half an hour at 250 degrees F. This will help combat any unpleasant burned smells that are left from the cleaning process.