Dough: Mix water and milk and lightly warm to at 30C, add sugar and active dry yeast. Activate yeast for 10min and then combine with salt, oil and sifted flour. Knead the dough. Grease the bowl with a little oil, transfer the dough and cover with plastic film. Leave at room temperature for 1.5hours for fermentation. After fermentation fold back the dough and split into 8 equal pieces.
2
Cheese filling: Grate Mozzarella and Grana Padano (medium grater). Crush feta with hands. Combine all the cheeses together, add salt and pepper to taste. Add milk and mix well.
3
Making Khachapuri: Every piece of dough open with the rolling pin into a round disk of 5mm thick. Put 2tbs of cheese filling in the middle of every piece and close the edges in the shape of a boat. Turn the stitch down onto a worktop and roll out lightly dusting with flour. Using a sharp knife make a cut lengthwise every boat and form the boards leaven the middle open. Bake Khachapuri in a preheated oven 200C for 15-18min. Put another piece of butter and a egg yolk in the middle of every Khachapuri and stay in the oven for another 3min. Serve hot.