Grease a large casserole dish and set it aside. Preheat the oven to 400°F.

Cook the shells according to package directions but leave them al dente. Drain, rinse briefly, and set them aside.

In a large skillet, heat the oil over medium heat. Turn the heat to low-medium, add the garlic and saute for 1-2 minutes. Add half the spinach and mix to coat it in oil. Once it has wilted down a little, add the rest of the spinach. Mix to coat and cook until wilted. Set it aside.

Drain the tofu, break it into quarters. Place the quarters and salt in a food processor and blend until smooth. Add the spinach mixture, lemon juice, and basil and pulse until the spinach is chopped up. Salt and pepper the filling to taste.

Add 1 cup of marinara to the casserole dish and spread it to cover the bottom.

Stuff each shell with about 2 tablespoons of the tofu mixture and place them in the dish. Cover the shells with the remaining marinara sauce and sprinkle with mozzarella cheese.

Cover the casserole dish with foil and bake for about 25 minutes. Uncover and bake for another 5 minutes or until cheese is bubbling.