Preheat oven to 400℉. Spray your 9x13 inch baking dish with olive oil.
Heat 1 teaspoon olive oil in a large skillet over medium heat. Add in the spinach and sauté for 1-2 minutes - until just wilted. Transfer to a plate and set aside. Next, heat the remaining olive oil in the same skillet and sauté the mushrooms for 4-5 minutes. Transfer to the plate and set aside.
Peel, halve lengthwise and deseed the butternut squash. Using a hand held mandoline slice it about 1/8 to 1/4 inch thick pieces.
In an extra large bowl, add in the Boursin, eggs, milk and whisk together until smooth. Next, add in the flour, baking soda, salt, garlic powder, onion powder, nutmeg and mix until incorporated. Then, fold in the parsley, spinach, mushrooms and butternut squash to coat all with the mixture. Transfer mixture to the baking dish and spread out evenly and flatly. Top with mozzarella and parmesan. Bake for 40-45 minutes or until golden brown on top.