Prepare 2 baking sheets with non-stick mats or parchment paper.
Trim the ends of each zucchini and slice them into about a ¼ inch long-sliced noodles.
Brush each side of each noodle with oil and place on the baking sheets.
Bake the zuchini slices in the oven for about 15 minutes or until they are tender but not too soft that you can't lift them in one piece.
In a 9-inch baking dish, or other size baking dish, place a thin layer of sauce on the bottom.
Next, add a layer of zucchini on top of the sauce. Spread about a tablespoon of ricotta cheese on each zucchini slice and then some sauce on top of the cheese. Continue this layering until you have at least 3 layers of zucchini, sauce, and cheese. Place a final layer of cheese and sauce on the top layer.
Bake the lasagna in the oven 400°F (200°C or gas mark 6) for about 15 minutes or until the sauce is bubbling.
Serve very warm. Store leftovers in the refrigerator for several days.