For the dough: rub sugar with eggs and butter, add sour cream and mix thoroughly. Then add 3-4 cups of flour in portions to make a soft, elastic dough. Divide the dough into 2 parts: 2/3 and 1/3.
Remove pits from cherries, sprinkle with cornstarch and toss to combine.
Roll out most of the dough and place on a baking sheet so that the edges of the dough hang slightly from the sides. Put berries on top, sprinkle with sugar.
Fold the edges of the pastry over the berries. From the remaining dough, roll up several long sausages and build a “lattice” out of them on top of the berries. Brush the dough with egg. Bake at 180°C for 40 minutes. Cool, sprinkle with powdered sugar.