PREHEAT oven to 375 degrees.
SAUTEE onions and mushrooms in olive oil until tender.
ADD spinach leaves during the last minute of cooking.
SEASON to taste with salt & pepper.
PLACE butternut squash into 9×13 greased baking dish and spoon cooked veggies over it.
TOP with shredded mozzarella and then bread cubes, pushing cubes down into the veggies.
POUR whisked eggs over veggies, cheese and bread, covering and moistening all bread cubes in the process.
SPRINKLE with dried Italian seasoning or fresh herbs and bake at 375 for 30 minutes or until cooked through.