Preheat the oven to 350°F
Soak the noodles while you're getting everything together. When softened, drain well.
Put about 1/4 cup of sauce in the bottom of the loaf pan. Cover the bottom with two of the noodles, cutting them to fit.
Spoon half the prepared butternut squash into the loaf pan. Add a little sauce and some of the shredded cheese.
Cover with more noodles, then add the spinach and mushroom layer, more sauce, more cheese.
Repeat again with the rest of the butternut squash, more cheese and more sauce.
For the final layer, cover the butternut squash with noodles, any cheese and the remaining sauce.
Cover with foil and bake for 20 minutes or so. Then remove the foil and bake for another 10 - 15 minutes or until the cheese is nicely browned and the sauce is bubbling.