Prepare the cheese: Shred both the Gruyère and Emmental cheeses and set them aside. Toss the shredded cheese with cornstarch to coat the cheese evenly.
- Prepare the fondue pot: Rub the inside of a fondue pot or heavy-bottomed saucepan with the cut sides of the garlic cloves to infuse a subtle garlic flavor. Discard the garlic after rubbing the pot.
- Heat the wine and lemon juice: Add the wine and lemon juice to the pot and heat over medium heat until the wine is warm but not boiling. Stir occasionally to prevent the wine from scorching.
- Melt the cheese: Gradually add the cheese in small handfuls, stirring constantly in a figure-eight motion. Allow the cheese to melt slowly and evenly.
- Add the kirsch (optional): Once the cheese has melted and the mixture is smooth, stir in the kirsch for added flavor.
- Season the fondue: Season with freshly ground black pepper and grated nutmeg to taste. Adjust seasoning as needed.
- Serve the fondue: Transfer the pot to a fondue stand with a burner underneath to keep it warm. Serve with bread cubes, vegetables, fruit, and charcuterie. Use fondue forks or skewers to dip ingredients into the cheese.