Acharuli Khachapuri is a Georgian bread stuffed with cheese and baked in the oven until molten and sizzling hot. An egg yolk is added during the last minutes of cooking, and the whole delicious mess is topped with a pat of butter. When the cheese, yolk, and butter are swirled together, it’s a thing of beauty.
- Preheat the oven to 500°F with a pizza stone/steel or baking sheet, the latter turned upside down. Heat for at least 1 hour.
- Combine the flour, yeast, salt, and sugar in a bowl. Make a well in the middle. Add the water, milk, and olive oil. Use a spatula or spoon to work the flour into the liquid. Continue until it forms a shaggy ball.
- Lightly flour your work surface. Knead the dough until smooth, about 5 minutes. Lightly oil a bowl. Place the dough in the bowl, cover with plastic or cloth and place in a warm place until doubled in size, about 1 to 1½ hours. Punch down and divide the dough in half. Form into rounds. Keep covered and let rest for 20 minutes while you prepare the filling.
- Combine the cheeses and whole egg. Add a splash of feta brine or milk so that the cheese just forms a paste.
- On a piece of lightly floured parchment paper, roll one piece of dough into a 10" to 12" oval about 1⁄8" thick. It doesn't need to be exact. Spread half of the cheese mixture over the dough, leaving a 1⁄2" border all the way around. Roll one of the long sides of the dough toward the center so it overlaps with the cheese a bit. Repeat on the opposite side. Pinch the two narrow ends of the rolls together and twist twice to seal, making a boat shape. Top with a generous handful of grated sulguni or mozzarella. Brush the dough with egg wash.
- With a pizza peel, transfer the bread to the hot stone. Cook until the cheese mixture is hot and bubbly and the dough golden brown, about 9 to 10 minutes. Remove from the oven. Using a fork, make a small well for the egg yolk. Pour the egg yolk with a little bit of the egg white into the well. Place back into the oven and cook another 2 to 3 minutes, until the cheese is bubbly.
- Remove from the oven and add a tablespoon of butter. While still hot, take a fork and swirl the cheese, yolk and butter together. Sprinkle with red pepper flakes. Tear off a piece of bread and scoop up some of the molten cheese. Repeat with the other half of dough.