Preheat your oven to 425°F and line a baking sheet with foil lightly misted with cooking spray.

Place cubed butternut squash and apples into a large bowl. Drizzle in about 2 tablespoons of oil. Sprinkle over salt and black pepper, along with 1 tablespoon of the maple syrup, the dried sage and the Herbes de Provence. Toss to coat.

Turn the mixture out onto your prepared baking sheet and roast for about 35 minutes, stirring occasionally for even roasting, or until the squash is tender.

While the butternut squash and apples roast, place a large skillet over medium-high heat and add a small drizzle of olive oil. Once the pan is very hot, add the crumbled sweet Italian sausage and cook until browned and cooked through, a few minutes. Remove from the pan and keep in a bowl.

If additional oil is needed in the pan, add a small amount. Then add the sliced fennel and onion into the pan and caramelize together for about 10-12 minutes, or until deeply golden and a bit jammy in texture. Remove from pan and add to the sausage.

Once the butternut squash and apples are tender and roasted, switch your oven setting to broil.

To prepare the casserole, carefully spoon the roasted butternut squash and apples into a large bowl and add the sausage, fennel and onion mixture. Pour in the remaining 1 tablespoon maple syrup and toss to combine (add a touch more salt and pepper to create a sweet-savory flavor). Spoon into a medium size baking dish.

If preparing fried sage leaves as a garnish, heat about 1/4 cup of oil in a small sauce pan or pot. Once shimmering, add the sage leaves and fry for about 20 seconds, then remove and drain on paper towels. Sprinkle lightly with salt and set aside.

To finish the casserole, top with the grated Gruyere cheese and place into the oven under the broiler for a few minutes, until the cheese is melted and golden-brown. Garnish with sage leaves and serve.