French Onion Soup Fondue

Melt butter in a large saucepan over medium heat. Add onions and cook, stirring occasionally, until caramelized and golden brown, about 20-25 minutes. Add garlic and cook for 1 minute more.

Deglaze the pan with sherry, scraping up any browned bits from the bottom. Add beef broth and thyme. Bring to a simmer and cook for 5 minutes, allowing the flavors to meld.

While the onion mixture simmers, toss the shredded cheeses with cornstarch in a bowl to prevent clumping.

Reduce the heat to low. Gradually add the cheese mixture to the onion mixture, stirring constantly with a figure-eight motion until the cheese is completely melted and smooth. Be careful not to overheat the fondue, as it can become stringy.

Stir in the Kirsch (if using) and a pinch of nutmeg.

Transfer the fondue to a preheated fondue pot and keep warm over a low flame.

Serve immediately with cubed crusty bread and sliced apples for dipping.