Stir the cornstarch and Kirsch in a cup until the cornstarch has dissolved. Alternately you can put the shredded cheese in a resealable bag with the cornstarch and shake until the cheese is coated.
Gradually add cheese to pot and cook, stirring constantly in a zigzag pattern (not a circular motion) to prevent cheese from balling up, until cheese is just melted and creamy (do not let boil). Stir cornstarch mixture again and stir into fondue.
Bring fondue to a simmer and cook, stirring, until thickened, 5 to 8 minutes.
Transfer to fondue pot set over a flame and serve with bread for dipping.