Place sweet potatoes in a pot and cover with water by 1-inch, salt water generously. Bring to a boil, then reduce to a simmer and cook until tender, about 15-20 minutes. Drain and return potatoes to the pot. Add the coconut cream, butter, ginger, and nutmeg. Mash until smooth, and season generously with salt and pepper. Transfer to a 2-quart baking dish. Top wtih marshmallows and coconut. Bake until the marshmallows and coconut are lightly browned, about 15 to 20 minutes. Serve immediately.