Saute mushrooms until tender. I saute them in a little water to keep it low fat, but you could certainly use oil.
Place the tofu, sugar, soymilk, garlic powder, lemon juice, basil, and salt in a food processor or blender and blend until smooth. Transfer to large bowl, and stir in the spinach. (make sure the spinach is drained!).
Cover the bottom of a 9-inch-by-13-inch baking dish with a thin layer of tomato sauce, then a layer of noodles. Follow with half of the tofu filling. Continue in the same order, using half of the remaining tomato sauce and noodles and all of the remaining tofu filling. End with the noodles, covered by the remaining tomato sauce.