How do you write an essay at the last minute?

1) Find a copy of another answer... use it as a base, look at the way that they've mapped out the essay (or a similar essay if you can't find the same one!)

2) Read through your books (and other books referenced).. don't literally read and then write.. read EVERYTHING.. then go back and try again...

3) Write an essay plan.. order your thoughts

Try whatever works for you... I tend to find puzzles (like a Rubix cube) are good for getting you thinking logically.. but try everything until you find something that works :)