Rub the inside of a fondue pot with the cut surface of garlic. In the pot combine Gruyere and Swiss cheeses, the 1 cup white wine and the lemon juice. Cook and stir over medium heat until cheese melts. Remove from heat.
In a very small bowl or custard cup thoroughly combine cornstarch, kirsch, nutmeg, and pepper. Add to cheese mixture. Cook and stir until mixture is thickened and bubbly.
Place fondue pot over heat source, and keep mixture bubbling gently. Serve with bread cubes for dipping.