To make the cream cheese filling
Add the cream cheese, roasted garlic and salt to a bowl and whisk until smooth and thoroughly combined.
Add to a piping bag and set aside until needed.
To make the butter mix
Whisk your egg until the yolks and white are fully incorporated, then add the rosemary, butter and a pinch of salt.
Assembly
Create 6 slits in each of your buns which are about 3/4 way through the rolls.
Pipe the cream cheese mixture into the holes then cover the slits with mozzarella. Slightly press the cheese into the filling to make sure it stays put for the next step.
Dip the top side of the buns into the butter and egg mix and swirl it around for a few seconds to make sure it's thoroughly coated and so it can suck up some of the mixture.
Place on a lined baking tray and bake in a 180˚C oven for 10-15 minutes until the cheese is melted and slightly golden.