1. Cut the 3 cheeses into small cubes.
2. Rub the caquelon with the garlic clove and leave it inside.
3. Pour 25 cl of white wine and heat it.
4. In a small container, pour the remaining white wine (5 cl), cornstarch, and nutmeg. Stir and set aside.
5. When the wine is simmering, pour the cheese (in several times) while stirring continuously (with a wooden spatula) over low/medium heat.
6. When the cheese is well melted, pour the glass of wine/cornstarch/nutmeg and continue stirring gently.
7. The mixture starts to become creamy and frothy, still a little liquid. Season with pepper and pour in the kirsch. It's ready to serve!
8. The egg yolk should be added to the caquelon when there is no more liquid left, in order to scrape the remaining cheese from the bottom.