Trim the ends from the zucchini. Using a Y-shaped vegetable peeler, slice each zucchini lengthwise into thin ribbons. You should get about 15 ribbons from each zucchini, for a total of 45.
Preheat the oven to 375°F. Spread the marinara sauce evenly in the bottom of a 9×13-inch baking dish.
In a large bowl, combine the ricotta cheese, egg, ¼ cup Parmesan cheese, basil, garlic, salt, and pepper.
Arrange 3 zucchini ribbons on a work surface, overlapping them in the center to form a star shape. Place about 2 tablespoons of the ricotta mixture in the center. Fold the ends of the zucchini ribbons over the filling to create a packet.
Sprinkle the mozzarella cheese and the remaining ¼ cup Parmesan cheese on top.
Place the zucchini ravioli seam-side down over the marinara sauce. Repeat with the remaining zucchini ribbons and filling to make 15 ravioli. Arrange the cherry tomatoes around the ravioli, if using, and sprinkle the mozzarella evenly on top.
Bake uncovered for 30 to 35 minutes, until the zucchini is tender and the cheese is melted. Let rest for 5 minutes before serving. Garnish with additional basil.