Pillowy bread boats stuffed with molten mozzarella and topped with a golden egg yolk, crispy guanciale, Parmesan and black pepper.
Mix the flour, yeast, sugar and salt in a large bowl, then add the warm water and olive oil and bring together into a dough.
Knead for 10 minutes until smooth and elastic, then place in a lightly oiled bowl, cover and leave to rise in a warm place for about 1 hour until doubled in size.
Knock back the dough and divide into 4 equal balls, then roll each into an oval roughly 20–25cm long.
Pile grated mozzarella into the centre of each oval, pinch the long edges together to seal and shape into a boat, pinching the ends tightly.
Flip the boats over, score down the centre with a knife and gently open them back up to expose the cheese and form a cheeseboat.
Transfer to lined baking trays and bake at 220°C (200°C fan) for 12–15 minutes until puffed and deeply golden with molten cheese.
While baking, fry the guanciale over a low heat until crisp, then set aside.
Remove the khachapuri from the oven, add an egg yolk to the centre of each, scatter over the guanciale and a generous shower of Parmesan. Return to the oven for 1–2 minutes just to take the chill off the yolk.
Mix the yolk and guanciale into the molten cheese with a fork and finish with lots of black pepper and extra Parmesan.