Rub the pan with the garlic clove, then leave the clove inside.
Pour 25 cl of dry white wine into the skillet and heat over low heat.
In a small bowl, mix the remaining 5 cl of white wine with the cornstarch and nutmeg. Set aside.
When the wine begins to simmer, gradually add the cheeses, stirring constantly with a wooden spatula over low to medium heat.
Once the cheeses have melted completely, stir in the mixture of white wine, cornstarch, and nutmeg, then continue stirring gently.
Let it thicken until the mixture is creamy and slightly frothy, while still maintaining a smooth consistency. Season with pepper to taste and serve immediately.
Add the egg yolk to the skillet when there is almost no mixture left, so you can scoop up the last bits of melted cheese from the bottom of the pan.
