To really do it right, you'll need sulguni cheese, a Georgian product that melts like mozzarella but with a far more pronounced tang. But that's a hard one to find, even in Georgian communities, so we suggest substituting Muenster and feta instead. That and a little butter to set over the top of the bread after you crack an egg to heat gently over the bubbly cheese. In a Georgian home, each person may be expected to finish their own khachapuri before carrying on with the main courses. That's an admirable goal, but you'll more than get by with just a couple for a crowd.