Cook Lasagna Noodles: Cook the lasagna noodles according to the package instructions until al dente. Drain and set aside.
Prepare Filling: In a large bowl, mix together the cooked lentils, chopped spinach, mushrooms, vegan ricotta cheese, nutritional yeast, minced garlic, dried oregano, dried basil, salt, and pepper until well combined.
Assemble Roll Ups: Lay out the cooked lasagna noodles on a clean surface. Spread about 2 tablespoons of the filling mixture onto each noodle. Roll up the noodles tightly and place them seam side down in a baking dish.
Top with Marinara Sauce: Pour the marinara sauce evenly over the rolled up lasagna noodles.
Bake: Preheat your oven to 375°F (190°C). Cover the baking dish with foil and bake for about 25-30 minutes, or until the roll ups are heated through and the sauce is bubbly.
Optional Topping: If desired, sprinkle vegan mozzarella cheese on top of the roll ups during the last 5 minutes of baking, and let it melt.
Serve: Once done, remove from the oven and let it cool for a few minutes. Garnish with fresh basil leaves if desired, then serve and enjoy!