Rub the base and sides of a heatproof casserole with the cut clove of garlic.
Pour in the wine reserving 2 tablespoons for blending the cornflour.
Toss in the grated cheese and heating gently and stirring continuously, bring the mixture to just below boiling point when the cheese will have melted.
Blend the corn flour with the reserved wine and stir into the fondue with the Kirsch if used.
Season to taste and allow to cook gently for a minute or two.
Transfer to spirit lamp or plate warmer, and keep warm.
The mixture should be of a coating consistency and will thicken as it cools.