Preheat your oven to 425°F (220°C).

Grease the bottom of your 9x13 inch baking dish.

In the baking dish, toss together the cubed butternut squash, cauliflower florets, sliced shallots, olive oil, Italian seasoning, and some salt and pepper.

Place the baking dish in the preheated oven and bake the vegetables for 30 minutes.

While the vegetables are baking, heat a large skillet over medium heat and add the ground Italian sausage. Cook it while breaking it up with a spoon until it turns brown and is no longer pink.

Drain as much of the grease as you can.

Pour in the dry white wine into the skillet with the sausage and allow it to cook down for about 3 minutes.

Add the chopped sage, minced garlic, red pepper flakes, and salt and pepper, cooking this mixture for an additional minute.

Gradually pour in the heavy cream, stirring as you go. Bring to a boil, then lower the heat and simmer for two minutes. Stir in the grated Parmesan cheese.

Once vegetables have roasted for 30 minutes, reduce the oven temperature to 350°F (175°C) and pour the sausage and white wine sauce mixture over the roasted vegetables.

Gently stir to combine everything, then sprinkle Parmesan and shredded mozzarella cheese evenly over the top.

Return the casserole to the oven and bake for 20 minutes.

Turn on the broiler and broil for 3 to 5 minutes until the cheese turns golden brown.

Allow the casserole to rest for about 10 minutes before serving.