Wonderful Mashed Potatoes

3 lbs potatoes, peeled and quartered
¼ lb butter
½ 1 c milk
½ c sour cream
2 t salt
½ t ground pepper
Cook the potatoes in a large pot of boiling salted water for 15-20 minutes until very tender. Meanwhile heat the butter and milk in small sauce pan (or in microwave) Drain potatoes. While still hot, place the potatoes in a big bowl. Slowly add the milk and butter mixture, sour cream, salt and pepper. Mix until the potatoes are mashed but not completely smooth.