Gently heat the milk until warm then mix it with the sugar and yeast in a large bowl. Leave for 10 mins to activate the yeast.
Separate 1 egg yolk for the egg wash and add the egg white + 2 whole eggs into the mixture.
Sift in the flour with the salt and mix all until you have a smooth dough. We are after a soft dough, slightly sticking to your hand. Add more water or more flour until you have the right consistency.
To shape the buns, cut the dough into 2 equal pieces and form them into balls, cover them with a clean kitchen towel, and let them rest for 10 minutes.
On a lightly floured surface, roll out the first ball to a large rectangular shape using a rolling pin. (Approximately 18" x 10" - 45 cm x 25 cm).
Spread half of the soft butter on the dough.
Mix feta cheese and kashar cheese for filling and sprinkle half of it on the dough.
Tightly roll the dough from the long side to the long side to turn it into a log.
Divide the log into 10 equal pieces with a serrated knife.
Repeat the same procedure for the second dough ball and place the buns in a greased baking tray, size of 12" X 8" (30 cm x 21 cm). When placing the buns in the baking tray, try to leave some space in between them. They will double the size during the rising and cooking period.
Egg wash the buns, cover the tray with cling film or damp cloth and leave it to rise in a warm place.
Preheat the oven to 356° F/180° C (fan oven).
Sprinkle on sesame seeds or nigella seeds.
Cook for 35 to 40 mins or until golden brown.