Preheat oven to 375°F.
Whisk together cream, pumpkin purée, spices, orange juice and zest, salt and pepper.
Grease the bottom of a 10” square baking dish with butter. Arrange an even layer of sweet potatoes on the bottom of the dish and drizzle the top with 3 tablespoons of the cream mixture. Season with salt and pepper.
Repeat procedure, pressing down until the potatoes are totally submerged in the cream mixture. Cover the top with cheddar, if using.
Cover with aluminum foil and bake 30 minutes. Uncover and bake an additional 30-45 minutes, until cream is absorbed and the top is brown. Let rest for 10 minutes before slicing.