Step 1Grate or dice the Gruyere de Beaufort, Gruyere de Comte, Appenzeller, Morbier and Roquefort cheeses and mix them in a bowl.
Step 2Rub the inside of a fondue pot or heavy pot with the garlic clove. Pour in the wine and bring it to boil over medium heat. Gradually incorporate the cheese mixture, stirring constantly in a figure-eight pattern with a wooden spoon.
Step 3When the cheese is entirely melted, about 20 to 25 minutes, add salt, pepper and nutmeg to taste. Stir in the mustard and kirsch.
Step 4To serve, set the fondue pot on the table over a fondue burner and let diners spear pieces of bread with fondue forks and plunge them into the fondue. Stir the fondue frequently (always in a figure-eight pattern) to keep it from separating or sticking to the bottom.
Step 5When the fondue is nearly finished, clean up the pot by putting in some pieces of bread, adding the egg and stirring with a wooden spoon until the mixture thickens. Let diners pick out the pieces of bread with their fondue forks.