Root Vegetable Gratin

2 1/4 pounds root vegetables, peeled and shredded (The original recipe calls for 3/4 pound each sweet potatoes, celeriac, and turnips, but many combinations will work well. Parsnips, carrots, and rutabagas are all good in this dish.)
1 1/4 cups heavy cream (It has to be heavy cream. Half and half will curdle.)
1/4-1/2 teaspoon cayenne pepper
salt and black pepper to taste
Optional topping: 2 tablespoons shredded cheddar cheese, 1 tablespoon dry breadcrumbs

 Preheat oven to 400/ F.
In a large bowl, combine the shredded vegetables, cream, cayenne, salt, and pepper.
Spoon mixture into a shallow gratin dish or baking dish. Cover tightly with foil.
Bake for 30-40 minutes, or until the vegetables are cooked.
Optional: remove dish from oven, heat broiler, combine cheese and breadcrumbs, sprinkle over the vegetables, and boil uncovered until the cheese is brown and bubbly.