Rustic Cheddar Mashed Potatoes

2 lbs. russet potatoes, peeled and diced

1 c. water

1/3 c. butter, cut in small pieces

½ to ¾ c. milk

1 ¼ tsp. salt

½ tsp. black pepper

½ c. finely chopped green onions

2-3 oz. shredded cheddar cheese

Combine potatoes and water in slow cooker; dot with butter. Cover and cook on High for 3 hours or on Low for 6 hours or until potatoes are tender. Using an electric mixer on medium setting, whip potatoes until well blended.  Add milk, salt, and pepper and whip until well blended.  Stir in green onions and cheese, cover tightly and let stand 15 minutes to allow flavors to blend and cheese to melt.