Bring the dried red lentils and 3 cups water to a boil in a medium pot, then lower the heat and simmer for about 20 minutes. Drain the lentils through a fine strainer when they are tender, then return them to the pot and stir in both jars of marinara.

Heat the oven to 350 °F. Give the oven time to fully preheat while you prepare the ricotta and assemble the casserole.

Process the cashews in a food processor until finely ground, then add the tofu, nutritional yeast, lemon juice, salt, basil, oregano, and garlic powder. Pulse until the mixture is blended and thick with a lightly crumbly texture; add a few tablespoons of water only if it will not blend.

Spread about 1 cup lentil marinara over the bottom of a large 9x13-inch casserole dish, then arrange 4 to 5 uncooked noodles over it. Cover the noodles with half the ricotta, half the spinach, and about 1 cup sauce before repeating with another noodle layer, the remaining ricotta, spinach, and a final layer of noodles.

Pour the remaining lentil marinara evenly over the top, covering exposed pasta edges, then seal the dish tightly with foil. The sauce should reach across the entire surface so the top noodles can soften rather than dry out.

Bake the covered lasagna for 40 minutes. The sealed foil traps steam, allowing the dry noodles to cook through inside the saucy layers.

Prepare the Easy Vegan Mozzarella Cheese while the lasagna bakes, if using, or have the shredded vegan mozzarella ready. The topping should be ready to add as soon as the foil comes off, keeping the second bake smooth and efficient.

Remove the foil, add the vegan mozzarella, and bake uncovered for 20 minutes more. Take the dish out when the topping bubbles and the edges look golden, then rest it for at least 15 minutes before slicing.