Sift together the baking powder and flour in a medium size bowl, set aside.
In a large bowl mix the remaining ingredients, except the milk, until smooth and well combined.
Alternately add the flour mixture and milk to the potato mixture.
Chill 30 minutes
On a lightly floured surface, roll out dough to about 1/4" thickness(thicker for fatter doughnuts). Cut using a doughnut cutter or use a glass but lightly flour rim before using. Cut out center using a smaller diameter circle.
Heat oil to 350 degrees
Carefully add dough to hot grease. Flip after doughnuts have reached desired color. Do not pierce the doughnuts when flipping or they can become greasier. Let cook until desired color is reached and remove from oil.
Drain on paper towels. Repeat process until all the dough is gone. Powder sugar and cinnamon/sugar can be added when cooled. CAUTION: don't let the oil drop below 350 or get too hot because the results can be disastrous. You can end up with doughnuts filled with gooey centers (oil too hot) or they'll be loaded with oil (too cold).