Adjaran Khachapuri

7 g (¼ oz) fast-acting dried yeast
2 Tbsp. granulated sugar
200 ml (⅓ pint) lukewarm water
450 g (1 lb) organic white bread flour, plus extra for dusting
10 g (¼ oz) fine sea salt
Filling
100 g (about 3 oz) full-fat twaróg or ricotta cheese
250 g (9 oz) Ogleshield, raclette, or a mixture of Edam and Cheddar, grated
250 g (9 oz) feta cheese, crumbled
10 g (¼ oz) unsalted butter, sliced into 6 pieces
6 small eggs, plus 1 egg yolk

To make the dough, mix the yeast with the sugar, water, flour, and salt in a bowl. Cover the bowl with clingfilm and either leave in the refrigerator overnight or somewhere in your kitchen for an hour or so until doubled in size.
For the filling, mix the cheeses with the single egg yolk and use a fork to mash well.
Preheat the oven to its highest setting and heat a couple of baking sheets—or a pizza stone if you have one.
Flour your work surface really well. Cover your hands in flour and scrape the dough on to your work surface. Knead it in the flour a little if it’s too sticky. Divide the dough into 6 pieces (each piece should be about 100 g (3½ oz). Roll out each piece of dough on a lightly floured work surface into a 18 cm (7-inch) round. Stretch either side of each round to elongate and then pile 100 g (3½ oz) of filling in the centre, leaving a 5 mm (¼ inch) border around the edge. Bring two sides of the dough up to meet in the middle and pinch a seam together to seal, similar to a Cornish pasty. Press down with the flat of your hand to flatten it, then flip it over so the seam is face down. With a sharp knife, make a slash along the middle of the dough and push the sides open to expose the filling. Repeat with the rest of the dough and filling to make 6 khachapuris.
Slide the khachapuris on to the hot baking trays and bake for 10 minutes until the sides turn golden. Crack an egg into the centre of each, then bake for a further 2–3 minutes. To eat, pinch the dough from one end and use it to dip and mix the runny egg yolk into the filling.