In an 7 ½" x 9 ½" pan, pour ¾ cup marinara sauce. Next, place zucchini noodles on marinara sauce, overlapping each slice. Spread ⅓ of tofu ricotta over zucchini noodles. Sprinkle nutritional yeast on top of tofu ricotta. Pour ½ of walnut sauce on top.
Layer more zucchini noodles, then ⅓ of tofu ricotta, nutritional yeast, and rest of walnut sauce. Finish with layer of zucchini noodles, tofu ricotta, and nutritional yeast. Bake at 375° for 35 minutes.