Preheat your oven to 375°F (190°C) and lightly grease a 9x13-inch baking dish. Set it aside while you prepare the fillings.

In a food processor, combine the crumbled tofu, drained soaked cashews, nutritional yeast, lemon juice, garlic powder, and salt. Pulse until the mixture resembles fluffy ricotta cheese, scraping down the sides of the bowl as needed.

Heat the olive oil in a large skillet over medium heat. Add the chopped onion and minced garlic, sautéing until softened and fragrant, about 4 to 5 minutes.

Stir the cooked lentils, crushed tomatoes, and Italian seasoning into the skillet. Reduce the heat to low and let the marinara sauce simmer for 10 minutes so the flavors can fully meld together.

Fold the chopped fresh spinach into the warm tofu ricotta mixture until it is evenly distributed throughout.

Begin assembling the lasagna by spreading a thin layer of the lentil marinara sauce on the bottom of the prepared baking dish. Place a layer of oven-ready noodles over the sauce, slightly overlapping them.

Spread half of the tofu ricotta mixture evenly over the noodles, then top with another layer of marinara sauce. Repeat this process with another layer of noodles, the remaining ricotta, and more sauce.

Top with a final layer of noodles and the remaining marinara sauce, ensuring all noodles are fully covered in liquid so they cook evenly. Sprinkle the vegan mozzarella shreds evenly across the top.

Cover the baking dish tightly with aluminum foil and bake for 35 minutes. Carefully remove the foil and bake for an additional 10 minutes, or until the vegan cheese is melted and the edges are bubbling and golden brown.

Remove from the oven and let the lasagna rest for at least 15 minutes before slicing. This resting period allows the layers to set up for clean cutting; serve warm and enjoy!