Combine tofu, spinach, garlic, oregano, basil, and salt in food processor. Blend until smooth. Set aside.
Spread ½ cup marinara sauce over bottom of a 9 × 13 baking dish. Layer with noodles, then top with half the tofu mixture and ½–1 cup marinara sauce. Top with another layer of noodles, remaining tofu mixture, and another layer of marinara sauce. Finish with a third layer of noodles and remaining sauce.
Cover with foil and bake for 1 hour. Wait 10 minutes before serving.
Notes
You may add additional marinara sauce to this recipe if you like a juicier lasagna.