Step 1: Wash and trim the ends of your zucchinis. Using a mandoline slicer or a very sharp knife, carefully slice the zucchini lengthwise into thin, even strips, about 1/8 inch thick. You should aim for about 20-24 slices.
Step 2: Lay the zucchini slices out in a single layer on a clean kitchen towel or paper towels. Lightly sprinkle both sides with salt. Let them sit for 15-20 minutes to draw out excess moisture. Gently pat the zucchini slices dry with paper towels.
Step 3: If you haven’t already, soak your raw cashews in hot water for at least 30 minutes, or cold water for 4 hours/overnight. Drain and rinse the soaked cashews thoroughly.
Step 4: In a high-speed blender or food processor, combine the drained cashews, nutritional yeast, lemon juice, minced garlic, dried oregano, and a pinch of salt and black pepper. Add 2-3 tablespoons of water, starting with less and adding more only if needed, until you achieve a thick, creamy, and smooth consistency similar to ricotta cheese. Scrape down the sides as necessary. Taste and adjust seasonings.
Step 5: Transfer the cashew ricotta to a bowl. Stir in the fresh chopped parsley and basil. Mix until well combined.
Step 6: Preheat your oven to 375°F (190°C). Pour about 1.5 cups of marinara sauce into the bottom of a 9×13-inch baking dish, spreading it evenly.
Step 7: Lay one dry zucchini slice flat on a clean surface. Place about 1-2 tablespoons of the cashew ricotta filling at one end of the slice. Carefully roll the zucchini slice up tightly to enclose the filling.
Step 8: Place the rolled involtini, seam-side down, into the prepared baking dish on top of the marinara sauce. Repeat with the remaining zucchini slices and filling, arranging them snugly in the dish.
Step 9: Once all the involtini are assembled, spoon the remaining marinara sauce over the top, ensuring they are nicely covered.
Step 10: Cover the baking dish with foil and bake for 25 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the zucchini is tender and the sauce is bubbly. For a slightly browned top, you can briefly broil for 1-2 minutes, watching carefully.
Step 11: Remove from the oven and let rest for a few minutes before serving. Garnish with extra fresh basil or parsley. Serve warm.