1. Preheat the oven to 180°C. Grease a 9- by 13- by 2-inch casserole dish.
2. Use a the large holes box grater or the grating blade of a food processor to shred the potatoes into a large bowl.
3. Add the sour cream, Cheddar, soup, onion, salt and pepper. Turn the mixture into the prepared baking dish and sprinkle with the crushed crackers. Pour the melted butter over the top of the casserole.
4. Cover with foil and bake for 45 minutes, then uncover and bake until lightly browned on top, about 20 minutes more.