Preheat the oven to 375°F.
Cook the lasagna noodles according to package instructions, then drain and set aside.
In a large pot, heat the olive oil over medium-high heat. Add the chopped onion and garlic, and cook for 2-3 minutes until the onion is translucent.
Add the crushed tomatoes, tomato paste, dried oregano, dried basil, dried thyme, salt, and pepper to the pot. Stir well and let simmer for 15-20 minutes.
In a separate bowl, mix the crumbled tofu, nutritional yeast, chopped parsley, salt, and pepper.
Spread a thin layer of the tomato sauce on the bottom of a 9x13-inch baking dish.
Add a layer of cooked lasagna noodles on top of the sauce.
Spread a layer of the tofu mixture on top of the noodles.
Add a layer of spinach leaves and mushrooms on top of the tofu mixture.
Repeat steps 7-9 until all the ingredients are used up, ending with a layer of noodles.
Spread the remaining tomato sauce on top of the lasagna.
Sprinkle vegan mozzarella cheese on top of the sauce.
Cover the baking dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.
Let the lasagna cool for a few minutes before slicing and serving. Enjoy your delicious vegan lasagna!