Peel potatoes and shred on grater, or coarse disc of electric shredder. There should be about 3cups of shredded potatoes. Add onions to potatoes and mix well. Season with salt and pepper.
Heat butter in an 8-inch skillet. When it is hot, add potatoes. Reduce heat and let them brown on the bottom. When they have browned, add the cream and simmer until cream evaporates. Brush top with melted butter, or dot with butter, and set under a broiler to brown the top. Serve from the pan.