Preheat oven to 400 degrees F.
Peel the squash, deseed and cut into cubes. Place them on a baking sheet. Coat them with olive oil, salt and pepper. Roast the squash at 400 degrees for 45 minutes until it is tender. Remove and allow to cool for 15 minutes or so.
In the meantime, cook the rigatoni until it's slightly underdone. Drain and rinse with cool water and set aside. Lightly oil an 8 or 9-inch spring form pan (I used an 8 inch).
Once the squash is ready, transfer squash to a food processor add the egg, gorgonzola cheese, burrata cheese and the milk. Puree until smooth.
Heat the butter in a large skillet over medium-high. Add the onion and cook until the onion is soft, about 5 minutes. Add the garlic and cook another minute. Transfer the butternut squash puree to the skillet, add 2 cups of the chicken broth, the cayenne, 1 tablespoons chopped sage, nutmeg, crushed red pepper flakes, salt and pepper. Whisk to combine and cook about 2 minutes. If the sauce seems too thick add more chicken broth to thin, I used the full 3 cups.
Spoon about a 1/4 cup of the sauce into the bottom of the spring form pan. Grab the rigatoni and pack the rigatoni in the pan, standing on their ends. Pour the remaining sauce over the pasta. Push the sauce down into the holes as best you can. Cover with the mozzarella cheese.
Place in the oven for 15 minutes. Remove and top with the pepperonis, and bake another 10 to 15 minutes, or until cheese is browned and bubbly. Let sit 15 minutes before slicing and serving.
While the pie sits fry the sage, melt 1 tablespoon butter in a sauce pan. Add sage leaves. Cook on medium-low for 1 minute, flip and cook one more minutes or until the sage has darkened in color, but is not burnt. Remove from the heat and place the fried sage leaves on the top of the pie. Serve!