Preheat oven to 425℉ and line a baking sheet with parchment. On a box grater or in a food processor, grate zucchini. Using cheesecloth or a dish towel, wring excess moisture out of the zucchini. Transfer zucchini to a large bowl with eggs, garlic, oregano, 1 cup mozzarella, parmesan, and cornstarch and season with salt and pepper. Stir until completely combined. Transfer mixture to a prepared baking sheet and pat into a crust. Bake until golden and dried out, 25 minutes. Sprinkle with remaining 2 cups mozzarella, crushed red pepper flakes, and parsley and bake until cheese is melted, 8 to 10 minutes more.
Slice and serve with marinara.