In a bowl, combine crushed tomatoes, lemon juice, lemon zest, garlic, onion powder, oregano, basil, thyme, paprika, black pepper and sea salt.
Spread half the sauce in the bottom of a 13 x 9-inch casserole dish.
In a bowl, mash the tofu, lemon juice, nutritional yeast, basil, onion powder, oregano, salt, pepper and garlic until the consistency of ricotta or cottage cheese. Fold in the spinach until well combined.
Spoon even amounts of filling (about 1 ½ - 2 tbsp) filling into each pasta shell.
Arrange shells in the casserole dish and pour the remaining tomato sauce over top.