Cave-aged Gruyere is one of the most famous cheeses made by the Swiss, named after the town of Gruyeres, AOC protected and aged for 15 months. It is initially hearty and nutty, developing a stronger, richer flavour as it ages, with a touch of fruitiness. It is also used as a fondue cheese and popular in France to make croque-monsieur, and on top of croutons for onion soup.