The best cheese for the gooey cheese bread is a combination of tangy and salty feta cheese and mozzarella cheese. In this recipe we added a third cheese - Monterey Jack, for a little more flavor and texture. When substituting any of the cheese mixture it is important to remember the texture and flavor that go best with the egg and bread. Sulguni cheese, which is used in the traditional Georgian dish tastes sour with a moderately salty flavor - so a goat cheese will typically fit the flavor and texture profile. For added creaminess to the molten cheese you could also use cottage cheese or ricotta cheese.