The best way to get your hands on one is to visit Oloron-Sainte-Marie. The rousquille can be found along the Pyrenean chain and is even sold in supermarkets, but these ones will be factory-made.
The origin of this pastry is still somewhat vague. Espagnole, béarnaise or even Roussillon, don’t allow yourself to be distracted and taste it simply. Enjoy your trip to Oloron-Sainte-Marie by visiting a bakery/pastry shop in the city and trying one of these rousquilles. Recognisable by its round shape and white icing, they have a soft shortbread biscuit consistency which gourmands will love.