1. Prepare a 9×13″ baking dish or similarly sized casserole dish by lightly greasing with olive oil. Set aside.
2. Begin by making the homemade cheeses if you are making them from scratch. If you prefer, you could use store-bought vegan ricotta and vegan mozzarella, but making them from scratch is easier than you think!

for the homemade ricotta

1. Add all ricotta ingredients except for the spinach to a high-speed blender and blend until smooth and creamy, scraping down sides as needed (~2 minutes). It should be well pureed and not chunky. If the mixture needs some help blending, add water a little at a time until you’ve reached a thick, creamy, and smooth texture. Add in the spinach and pulse to break it up, but not completely blend it up – it should be flecked with green.
2. Taste and adjust as needed, adding more salt for overall flavor, nutritional yeast for cheesiness, and lemon juice for acidity. Transfer to a bowl and set aside.

For the tempeh mushroom marinara sauce

1. In a large saute pan, heat the olive oil until shimmering. Add in the tempeh and sauté until browned, about 5 minutes, stirring frequently.
2. Add in a little bit more oil, and add the diced onions and mushrooms. Sauté until the onions are translucent and the mushrooms have evaporated all of their water and are starting to brown slightly. Add the garlic and cook for another minute. Season to taste with salt and pepper.
3. Stir in one jar of the marinara sauce. Bring to a simmer to heat the tomato sauce through, and then turn down to very low to keep warm.
   

Assemble the lasagna

1. In the prepared pan, spread 1 cup of the plain tomato sauce on the bottom. 
2. Top with three uncooked lasagna noodles and spread about 3/4 cup ricotta evenly on top of the noodles. You can also spread some ricotta onto the noodles individually if that’s easier for you, and then lay them down. Top with 1 cup of the tempeh mushroom marinara.
3. Repeat with the noodles, ricotta, and tempeh sauce until you’ve used all your fillings and noodles. On top of the last layer, add 1 cup of plain marinara sauce. This will help ensure the noodles stay well hydrated and cook through.
4. At this point, you can store the lasagna tightly wrapped in aluminum foil in the refrigerator for up to two days, or bake right away.

To bake

1. When you’re ready to bake, preheat the oven to 375°F.
2. Cover with foil (if not already covered) and bake for 40 minutes.
3. While the lasagna is baking, make the vegan mozzarella. To make this, simply blend all of the ingredients for the vegan mozzarella in a high-speed blender for 2-3 minutes until completely smooth. It will seem a bit thin at this point, but will thicken in the oven.
4. Remove from the oven after 40 minutes and top with the vegan mozzarella cheese sauce. Return to the oven, uncovered, for 20 minutes, until the cheese is bubbling and beginning to brown. If you want it more browned, turn on the broiler for a minute or two – make sure to keep a close eye on it!
5. Remove from the oven and let it rest for about 15 minutes to help it cut more cleanly. Garnish with fresh basil and serve warm!