To the effervescent yeast add the oil, 1 whole egg and 1 white. Stir and to them add the flour with baking powder. Stir again. Make a well in the rest of the flour and pour the mixture in it. Knead a smooth, nonstick dough.
Put it in an oiled container, cover and wait for it to double in volume. Divide the dough into 2 parts and roll out into rectangles. Smear with the melted butter and sprinkle with feta cheese.
Cut it into wide strips and fold each strip into 2 lengthwise. Twist and arrange them in a spiral. Put baking paper in a tray and arrange the buns in it.
There's no need to rise again. Smear them with the yolk beaten with a few drops of oil. Bake in a preheated 356°F (180 °C) oven about 25 min.
Source: Ralitsa Nikolaeva.