In kefir add melted butter, sugar, yeast, yolk. Stir. Leave on for 5-10 minutes.
Sift flour, add salt. Pour the kefir mixture.
Make dough. Cover with a clean towel and clean in a warm place for an hour.
For the filling, RUB the cheese on a coarse grater. Add eggs and sour cream. Stir.
Approached the dough is divided into two parts to make it easier to roll out. On the flour-covered surface, roll out the dough with a thickness of 0.5 cm.
Cut out circles (diameter 8.5 cm), in half of the circles make holes.
In one circle put the filling, put on top of the "leaky" circle and zasiyaet region. I got 12 cheesecakes.
Spread on a baking sheet covered with baking paper, grease with egg white and put in the oven, heated to 180 degrees for 25 - 30 minutes until Golden brown.