Make the crespelles according to the referenced recipe and let them cool so they are easy to fill.
Preheat the oven to 375°F (190°C).
In a large bowl, combine the ricotta, 1 1/2 cups of the shredded mozzarella, the egg, squeezed spinach, grated Parmesan, 1/2 teaspoon kosher salt, and black pepper to taste; stir until evenly mixed.
Spoon about 1/4 cup of the spinach-ricotta filling onto each crespelle and roll them up tightly with the seam side down.
Spread 1 cup of marinara sauce on the bottom of a large baking dish (or divide between two smaller dishes).
Arrange the rolled manicotti seam-side down in the dish, then spoon the remaining 1 1/2 cups of sauce over the rolls and sprinkle the reserved 1/2 cup mozzarella on top.
Cover the dish with foil and bake for about 25 minutes, until heated through, sauce is bubbling, and the cheese is melted.
