Make the almond ricotta: drain the almonds and transfer them to a food processor or blender. Add a ¼ cup of the soaking water. Pulse the almonds until lightly creamy-looking. It should be lumpy like dairy-based ricotta. Add more soaking water if necessary to achieve the right texture.
Scrape the ricotta into a clean glass container and stir in the probiotic powder until evenly distributed. Cover the container with a clean dish towel, securing it with a rubber band. Place the ricotta in a warm spot and let it ferment for at least 8 hours. I like to put mine inside the oven with only the oven light on.
Check the ricotta at 8 hours and stir it up. It should have a lightly tangy flavour. I usually let mine go for a full 10 hours. Once it’s to your liking, stir in the olive oil, salt, garlic, and nutritional yeast (if using). Place a lid or some sort of tight seal on top, and store the ricotta in the refrigerator.
Make the pesto: toast the walnuts in a dry skillet over medium heat until fragrant and lightly browned, about 5 minutes. Transfer the walnuts to a blender or food processor. Add the garlic, lemon zest, lemon juice, spinach, olive oil, salt, and pepper to the blender as well. Pulse the motor until the contents are uniformly chopped. Then, run the motor on high until you have a chunky puree. You may have to scrape down the sides a few times as you mix. Set the pesto aside.
Make the lasagna! Set an 10/11-inch skillet over medium heat. Pour the olive oil in. Add the onions, carrot, and zucchini to the skillet. Saute until onions are translucent and edges of carrots are soft, about 5 minutes. Add the lentils, garlic, chili flakes, salt, and pepper. Stir and cook until garlic is fragrant, about 30 seconds.
Pour the tomato sauce in and stir. Bring the sauce and vegetables up to a simmer. Nestle the broken lasagna noodles into the sauce mixture in the skillet. Try to submerge them in sauce by pushing them around. Cover the skillet and gently simmer until the lasagna noodles are just-tender, about 15-17 minutes. Add ¼ cup of water and stir if the mixture seems to be drying out too fast.
Stir the vegetables and noodles, just to check that all the noodles softened up. Dollop the almond ricotta and spinach walnut pesto on top of the lasagna, pushing the dollops into the lasagna with the back of your spoon. Scatter a small handful of spinach here if you like. Place the lid on top and cook the lasagna for another 10 minutes.
Serve the lasagna hot with a drizzle of olive oil or pine nut parm, if you like.