Start by sautéing the mushrooms. To a pan over medium heat, add a drizzle of olive oil, then add in the mushrooms, onion & garlic powder, salt & pepper and stir. Sauté for 6-7 minutes, until the mushrooms become soft.
To a food processor, add the tofu, lemon juice, tahini, nutritional yeast, basil, garlic & onion powder, salt, pepper, spinach, and sautéed mushrooms. This will be your ricotta.
Note: if you are adding frozen spinach, microwave it for 1-2 minutes on high. Drain the extra water that it releases before adding it to the blender.
Blend the ricotta until all of the ingredients are well incorporated, but it's okay if you leave it a little bit chunky, if you prefer your ricotta that way.
Next, cook the lasagna noodles according to the package instructions.
Grab a large baking dish. Cover the bottom of the dish in a thin layer of pasta sauce.
Then cover the bottom with a layer of lasagna noodles. Top the noodles with a thick layer of ricotta. Then add more pasta sauce to cover the ricotta.
Repeat the layering of pasta sauce, noodles, and ricotta, until you reach the top of the pan. You can just top the top layer with more pasta sauce, but I decided to add vegan mozzarella slices. You can also add regular vegan cheese, tomatoes, or more ricotta.
Cover the lasagna with foil and bake it in the oven for 20 minutes at 400*F/ 200*C. Remove from the oven, uncover the lasagna, and bake for another 10 minutes. Enjoy!