A comprehensive final exam should give you an opportunity to show what you have learned. Since this is a writing course, you should have learned, or at least reinforced what you already knew, about how to be a successful writer. While I'm letting you start this paper today and finish it during the next class, it is tantamount to a final exam and is, therefore, an in-class essay. You are on your honor to write this essay in class only. While everyone goes through the same general phases or stages in producing a written product, we don't necessarily prefer to do them in the same order, at the same rate, using the same equipment or processes, or with the same results.
Writing is a uniquely individual act.
Think about the writing that you have done this semester and in the past. Your assignment is to write an essay of approximately 500-600 words in which you describe your writing process. In the paper, you will describe your process by analogy or in an extended metaphor, comparing it to some other process with which you are closely familiar. So relax, have fun, do well.