Think of the key words in each paragraph and they'll act as prompts.
Also, try and write the key sentence in a different colour, the evidence in another colour etc. etc. because colours are another memory prompt
Is it Philosophy by any chance? My friends are doing their timed conditions Philosophy essays at the moment. You just need to remember the key points, there's no point trying to learn all of it off by heart, depending on the length. It can be done, it depends if you're good at learning things off by heart in general. For my Italian oral I've had to memorise 2 A4 pages of arguments and I did most of it the space of a few days, I listened to some music, learned a sentence or two, listened to some more music, then learned some more, and so on! I just gave myself really short, regular breaks and kept reciting it aloud to myself.
Yeah think of one word of summary for each paragraph, then make a song or a rhyme with each word beginning with the first letter of each summary word in the appropriate order.
Other than that just write it out again and again, looking as little as possible.
And try to keep calm.
Why do you have to learn an essay anyways?
Learn the main points in bullet points, all I do, then just fill in the gaps when it comes to it, maybe remember a good intro and ending fully, but for r.e synoptic were just learning the main points inbetween and the intro and eval.
I find that this helps a lot. OK read the first line out loud then close your eyes and say what you ust read, read the next line and then close your eyes and read that line and the first one together without looking.