I have a self cleaning oven but it never gets the window clean. Wish I'd known this years ago!
CLEANING YOUR OVEN - The easiest way EVER! REPOST:)
Begin by preheating the oven to 150 degrees (or your lowest setting available). While the oven is heating, put on a pot of water to boil. Once the oven has reached 150, turn it off and pour 1 cup of ammonia into a heat safe bowl or baking dish and place it on the top rack of the oven. Place the pot of boiling water on the bottom rack, close the oven door, and leave them both in the oven overnight.