To make the cheese sauce, add the soaked and drained cashews to a high-powered blender or food processor with the water, nutritional yeast, lemon juice, garlic, and salt, and blend until smooth.
Preheat oven to 350 degrees F. Cook pasta in a large pot of lightly salted boiling water for 2 minutes less than the package instructs, then drain.
Stir together the pasta, marinara sauce, and half of the cashew cheese sauce in a 13 x 9-inch baking dish or casserole dish of a similar size.
Evenly spread the remaining cashew cheese sauce on top of the pasta to cover it. If desired, spoon small dollops of vegan ricotta onto the top of the pasta and press them down into the pasta.
For the finishing touch, evenly sprinkle the vegan parmesan across the top.
Bake for 25-30 minutes, then remove from the oven, allow to cool briefly, and serve!