In a small bowl, mix warm sour cream (slightly warmed), sugar, and yeast. Let it sit for 5–10 minutes until foamy.
In a large bowl, combine flour and salt. Add butter and rub it in until crumbly.
Add the egg and yeast mixture, then knead into a soft dough.
Cover and let the dough rise for about 1 hour, until doubled in size.
Roll out the dough to about 2 cm thickness. Fold it over itself (like a letter), then roll out again. Repeat this folding process 2–3 times for flaky layers.
Roll out the dough again and cut into small rounds using a cutter. Score the tops lightly with a knife.
Place on a baking tray, brush with egg, and sprinkle grated cheese on top.
Bake in a preheated oven at 190°C (375°F) for 20–25 minutes until golden brown.
