I had the chance to eat it a few times when I was younger but it was very rare. Not only this potato is difficult to get in the shops (it sells really fast) but it is also quite expensive. It now sells for about 6 euro per kilo. The first crop usually goes for auction and it once reached 2,285 euro for a box of 5 kilos!
The rare times I ate bonnotte potatoes, it was only boiled with the skin on and served with a sprinkle of fleur de sel (how handy it is that Noirmoutier also produces a lot of fleur de sel!). Nothing else added! And you would not need anything else, the quality of this potato is such that it melts in your mouth like butter, divine!