DirectionsCombine potatoes, sugar, eggs, and butter.
Sift together flour, baking soda, cream of tartar, salt, and cinnamon.
Add to potato mixture alternately with milk, ending with dry ingredients.
If dough is too wet to roll out, add a little more flour.
Chill 1 1/2 hours in fridge.
Turn out onto a well floured board and roll out 1/4" thick.
Cut with a floured doughnut cutter.
Fry doughnuts and holes in 360F.
Turn only once.
Drain on paper towels, then cool on a rack.
Leave plain or roll in cinnamon sugar.