Preheat oven to 400 degrees
Slice butternut squash into thin slices (1/2 cm thick. As the butternut gets closer to the core, your circles will be cut in half.
Dice mushrooms into small pieces and sautee with a pinch of salt and a touch of olive oil, about 5 minutes.
Prepare square dish by adding a layer of sauce, then a layer of butternut squash, sprinkle both cheese and 1/4 of the mushroom.
Add another layer of butternut squash and continue layer each of the previous ingredients for about 4-5 layers.
The top layer does not need mushroom, just sauce and mozzarella.
Cover with foil and bake for 45 minutes, remove foil and bake for another 10 minutes. Let it rest for a few minutes, the liquid will settle and serve.