In large bowl, place potatoes. Thaw in microwave on defrost. Add cream soup, milk and chip dip and 3/4 of shredded cheese. Place potato mixture into 9x13 baking pan. (may need to use additional small casserole dish in addition to 9x13 pan. Season with salt and pepper and dot with butter pieces. Cover with foil. Bake at 375F for about 30 minutes till bubbly. Remove foil and top with remaining shredded cheese. Return to oven and bake till cheese is bubbly and browned (about 20 minutes). Remove from oven and allow to set at room temperature about 10-15 minutes.