1 Tablespoon at a time. Fry 3-5 minutes or until golden brown all over. Carefully remove doughnuts from oil and place on paper towels to drain. Gently roll warm doughnuts in powdered sugar and set aside. Add remaining ingredients and beat well.
Drop spoonfuls into hot oil.
Fry quickly, drain and roll in icing sugar. In a 2 quart bowl with a flat bottom mash the hot peeled boiled potato and butter, using a hand masher. Add the farmer cheese and mash some more until uniform. Then add egg yolks and mix smooth. I add the yolks at this point so as to allow the cheese to cool the potato.