Preheat the oven to 425 degrees.

Slice the zucchini into ¼" rounds and place on a baking tray that has been lined with either parchment paper or aluminum foil. If you use aluminum foil, make sure you spray it with non-stick cooking spray.

Brush the top side of each zucchini with olive oil and season with salt and pepper.

Bake for 2 minutes and then flip each zucchini slice and brush with a little more olive oil, season with salt and pepper. Return to the oven for 1 to 2 more minutes.

Add a spoonful of marinara sauce to the top of each zucchini slice.

Add the mozzarella cheese.

Sprinkle Parmesan cheese on top.

Turn the oven up to broil and place the baking tray under the boiler for 1 to 2 minutes or until the cheese is hot and bubbly.

Let cool slightly before serving.