Pour a portion of enchilada sauce in the baking dish to coat the bottom completely (about 1/2 cup). Place 3 whole tortillas (6 halves) on top of the enchilada sauce. Layer 1/2 the refried beans then 1/2 the corn, onion, tomato mixture. Sprinkle with 1/2 the nutritional yeast, and then 1/2 the spinach. Repeat with a layer of tortillas then beans, corn, onion, tomato mixture, yeast and spinach. Top with remaining tortilla halves and then the remainder of enchilada sauce.