Among my favourites, Langoustines
you can buy them alive, take a few litres of water, add ground pepper and salt and bring to boil - put the langoustines inside - when water starts boiling again pour off the hot water and replace with cold water, just to stop cooking. It should be between 1 minute and 1.5 minutes of cooking time, no more otherwise they will turn chewy.
You can then eat them with mayonnaise, though I prefer to dip them in a mixture of olive oil, a few drops of lemon juice, salt and pepper. It could hardly be simpler. It's better to open them with your hands and some tools rather than with your teeth, it might hurt for a few days afterwards..
Among seafood in northern brittany, some people rave about Ormeaux
they are rather expensive though, say 30-60 euro a kilo at local fish stalls depending on size; it's a peculiar taste, love it or hate it kind
Among desserts there is the traditional cake Kouign Amann: seems like half a kilo of butter, half a kilo of sugar, a tablespoon of flour and then you go [img]/forums/images/graemlins/grin.gif[/img] well if you like croissants..