In a medium bowl, combine the Emmentaler, Gruyére, cornstarch, nutmeg, and pepper.
Smash the garlic clove or break it in half to expose some of the oils. Rub along the inside of the fondue pot. You can then discard the clove or leave it in the pot until right before serving for a more intense garlic flavor.
Add the wine and lemon juice to the fondue pot and turn the heat to medium. Once the liquid is simmering, around 4-5 minutes, turn the heat to low and slowly add handfuls of the cheese mixture while stirring. Continue stirring until the cheese is completely melted and smooth, around 8-10 minutes. Remove the garlic clove.
Enjoy cheese fondue with dippers immediately. Keep the heat on low and stir frequently to keep the cheese from separating or sticking to the bottom of the fondue pot. If the fondue becomes too thick, stir in an additional 1/2 - 1 tablespoon of wine.
Black pepper creates a speckled appearance in the cheese fondue. For a fondue that’s completely uniform in color, you can substitute white pepper.