Dissolve the sugar and yeast in the lukewarm milk, then knead with the flour, salt, yoghurt, egg and oil into a soft dough. Cover and let rise for 1 hour.
Knead two-thirds of the cheese with the egg, and shape into two balls; set the remaining cheese aside.
Divide the dough in two, flatten each into a round, place a cheese ball in the centre, and pinch the edges together into a bundle.
Turn seam-side down and flatten into a roughly 1 cm thick, 28 cm round.
Brush with egg yolk, and sprinkle evenly with the reserved cheese.
Bake in a 220°C oven for 15-18 minutes, until the dough and the cheese on top are golden brown.
Once out of the oven, brush with butter, and serve warm, cut into wedges.
A Receptnaptár original recipe. Calories and protein are estimated.
Tips
You can flash it under the grill for the last 1-2 minutes of baking, for patchy browning on the cheese.