If the lasagna noodles need to be cooked before use, do this first, following the instructions on packet, and then set them aside to cool slightly. It’s a good idea to cook with a T of oil, to prevent them sticking together.
Preheat oven to 400.
Ladle a bit of the warm sauce into the baking dish and spread it around so that the bottom of the dish is lightly coated.
Place lasagna noodles in the pan to form a single layer. If necessary, break noodles to cover gaps.
Sprinkle 1/3 of the tofu mixture on the noodles, then lay out 1/3 of the spinach on top of that. Cover with tomato sauce.
Repeat using 1/3 of the ingredients, then add the last of the noodles, ricotta, and spinach. Add the mozzarella, if using, then top with the rest of the tomato sauce.
Cover with foil and bake for 30 minutes, until sauce is bubbly. Let cool slightly and serve.