Slice the zucchini into paper thin rounds.

You can use a really sharp knife, or a mandolin. In the bottom of your dish add a tablespoon of the marinara. Layer on some of the zucchini. Carefully spread out 1 tablespoon of ricotta. Add another tablespoon of marinara. Layer on the second layer of zucchini, another tablespoon of ricotta, any leftover zucchini, and then the last tablespoon of marinara. Top with the mozzarella. Microwave for 3-4 minutes, depending on the strength of your microwave.

You can sprinkle on a little oregano or Parmesan cheese if you like.