Heat oven to 425 degrees. Drain, peel and shred potatoes. Toss them with salt and pepper and press into prepared pan. Melt butter and pour over potatoes. Bake on bottom rack of oven until bottom is golden, 40-45 minutes. Broil about 8 minutes until top is golden and crisp. Cut hash browns into squares and serve. (Can be made a day ahead and refrigerated until ready to bake.)