Rub the inside of a large, heavy based saucepan with the crushed garlic clove, then discard. Combine the wine and cornflour in the saucepan and whisk to combine. Bring to a boil over a moderate heat, then reduce to a simmer and stir in the grated cheeses.
Stir continuously until the cheese is smooth and melted, then season with the nutmeg and black pepper. Continue to cook over a low heat for 12-15 minutes until the fondue has thickened to the right consistency.
Transfer to a fondue pot and set over a portable flame to keep warm. Garnish with another small pinch of nutmeg and serve with the pieces of cubed baguette.