Preheat the oven to 400℉.
Now, slice the ends from the zucchini then slice them the long way. Try to get slices about 1/4 in thick. Avoid making them super thin.
On a sheet pan, place the zucchini then season with salt and pepper on both sides. Bake in the oven for 15 minutes. They will not be fully cooked but that isn't the goal. Remove the pan from the oven then begin to build the recipe in a baking dish.
In the baking dish, add a little sauce on the bottom then make a layer of zucchini. Next, add both cheeses, breadcrumbs and more marinara. Layer until you the final layer is a layer of cheese with breadcrumbs across the top.
Place the zucchini parmesan back into the oven for 20-25 minutes or until the cheese has melted on top.
Lastly, allow to cool before serving because the insides will be extremely hot.