Doughnuts with jam

Mix the cake flour, salt, sugar, and instant yeast together in a bowl. Heat the butter and milk in a pot until lukewarm. Beat the egg and egg yolk together and add to the flour mixture along with the heated milk. Knead the dough for approximately 10 minutes until it is smooth and elastic and does not stick to your hands. Cover the dough loosely with a piece of plastic and leave in a warm place for 10 minutes. Punch down and divide into 16 pieces each weighing about 50 g. Roll into balls and place on a greased baking sheet. Cover with a piece of plastic and leave to rise until doubled in size.
Heat oil for deep-frying. Fry the doughnuts for approximately three to four minutes until golden-brown. Drain on paper-towelling and leave to cool. Attach a long narrow nozzle to a piping bag filled with jam. Press a hole in each doughnut with the nozzle and squeeze some jam into each doughnut. Roll doughnuts in castor sugar and then sprinkle with icing sugar.
Makes 16 doughnuts.