In order to melt cheese all you need to do is add a certain degree of heat until the cheese becomes more pliable.
Usually this can be done by sticking cheese in the microwave for a minute or so.
Cheese is a combination of water and diary fat that is held together by proteins. When it is heated the proteins began to break and it becomes gooey.
So can gerbils eat melted cheese?
No, they cannot eat cooked food at all and this includes melted cheese.