Alpine forests are covered in bilberry bushes which, in the summer, yield lots of fruit. Bilberries are slightly tangier and darker than its bigger relative, the blueberry, and they are used in a multitude of dishes in the French mountain regions.
The 'tarte aux myrtilles' is perhaps the most famous local recipe made using these wild blueberries. It is made only with a simple tart crust on top of which sit the bilberries dusted with powder sugar. But you can also find bilberry jam, ice cream, crepes...
Even if you can find bilberries everywhere when you go for a hike in the Alps, you need to take care when picking them as in some National Parks foraging is forbidden. They can also be confused with a similar berry growing in the area, which should be eaten with caution. So your best bet is just ordering a 'tarte aux myrtilles' for dessert at your favourite restaurant in resort.