Preheat the oven to 350F. Cook the jumbo shells to al dente. Rinse with cool running water to cool the cooked shells down.
To make the tofu ricotta: In a food processor with a standard blade attachment, process together tofu, lemon juice, and 1 tablespoon olive oil until smooth. Add remaining tofu ricotta ingredients and process until smooth. This can also be done by hand using a potato masher or fork.
To cook the veggies: Heat a medium skillet over medium-high heat. Drizzle in 1 tablespoon olive oil. Once hot, add the mushrooms and salt. Saute 6-8 minutes, until the mushrooms are softened and golden. Add the spinach and garlic. Saute until wilted, about a minute.
Fold the mushrooms, spinach, and garlic into the tofu ricotta until well combined.
To assemble the stuffed shells: Add 2 cups of marinara sauce to an 8x8 baking dish. Spread to evenly coat the dish. Add a heaping tablespoon of the ricotta mixture to each shell. Layer shells in 3 rows of 5. Top with remaining marinara sauce.
Cover with foil or an upside down sheet pan. Bake at 350F for 15 minutes. Uncover and bake another 10 minutes, until the marinara sauce is bubbling and the filling is hot throughout.
Serve topped with additional basil. Enjoy!
Notes
You only need 15 shells in an 8x8 baking dish but I always cook extra just in case they break while being filled.
Fresh or frozen spinach can be used. Make sure to squeeze excess liquid out of the frozen spinach.
Leftovers: For best quality, keep leftovers refrigerated in a closed container for 3-4 days. Reheat individual servings in the microwave in about 2 minutes, or cover the baking dish and reheat at 350F for 15-20 minutes, until warmed through.
You can watch me cook this full recipe over on my YouTube channel.