Preheat the oven to 375°F (190°C).

Bring a large pot of salted water to a boil and cook the jumbo pasta shells according to the package directions until just al dente, then drain and let them cool slightly.

While the shells cook, heat the olive oil in a skillet over medium heat.

Add the finely diced zucchini to the skillet and cook, stirring occasionally, for 4 to 5 minutes until just tender, then remove from the heat and let it cool for a few minutes.

In a mixing bowl, combine the ricotta cheese, shredded mozzarella cheese, grated Parmesan cheese, chopped fresh parsley, chopped fresh basil, dried Italian seasoning, minced garlic, salt, and black pepper.

Add the cooked zucchini to the cheese and herb mixture and stir until everything is evenly combined.

Spread 1 cup of marinara sauce over the bottom of a baking dish.

Fill each cooled jumbo shell with a generous spoonful of the herb and zucchini ricotta filling and arrange the stuffed shells in a single layer in the baking dish.

Spoon the remaining 0.5 cup of marinara sauce over the tops of the stuffed shells and drizzle the water around the edges of the baking dish.

Cover the baking dish tightly with foil and bake for 20 minutes.

Remove the foil and bake for another 10 to 15 minutes, until the shells are heated through and the sauce is gently bubbling.

Let the Herb and Zucchini Stuffed Jumbo Shells rest for 5 minutes before serving so the filling can set slightly.