Butter an 8-inch springform pan and preheat oven to 375 degrees F.
In a large mixing bowl, place 2 1/2 cups squash flesh, 1 cup bread crumbs, eggs, grated cheese, mascarpone, nutmeg, salt and pepper, and stir to blend well. The resulting mixture will have a batter-like consistency. Use the remaining bread crumbs to dust the springform pan. Pour the batter into the pan and bake until set and a toothpick exits cleanly, about 30 45 minutes. Remove the pan from the oven and let it cool 20 minutes. Unmold on to plate and serve either hot or cold.