Rub the inside of your fondue pot or heavy-bottomed saucepan with the cut garlic clove. Discard the garlic.
In a small bowl, toss the shredded cheese with the cornstarch until evenly coated.
Pour the white wine and lemon juice into the pot and heat over medium heat until just simmering. Do not boil.
Gradually add the cheese mixture to the wine, a handful at a time, stirring constantly in a figure-eight motion until each addition is melted before adding more.
Continue stirring until the mixture is completely smooth and creamy.
Stir in the nutmeg and Kirsch, if using. Keep the fondue warm over very low heat or on a fondue warmer, stirring occasionally.
Serve immediately with bread cubes and your chosen dippers.
Notes
Shredding your own cheese prevents anti-caking agents found in pre-shredded cheese from causing lumps.
If the fondue becomes too thick while serving, stir in a small splash of warm wine or lemon juice to loosen it.
Keep the heat low during the melting process to achieve a smooth texture.