This is something I've wanted to try for a long while now. What put me off was the fact that it seemed to require quite a bit of effort, because most videos you see on YouTube feature meticulously laminated single-serving-sized pastries. But then I saw a guy from Douarnenez making the authentic version:
I think his name is Thierry Lucas and he can be seen in another YouTube clip:
Turns out it's super simple and can be made with everyday pantry ingredients and there's no need to be particular about lamination. I even had foil pie plates in the cupboard. (Ended up buying extra salty butter, because I wasn't sure how much salt they put in theirs in Brittany. Finnish extra salty butter is 2% salt.)
The dough was AP flour, 70% water, 2% salt, 1% dry yeast. Lucas' dough looked quite a bit looser. I think it's because he doesn't let it rest between the folds and it's easier to roll out.
500g of dough with 250 g butter and 250 g sugar is enough for cakes baked in 25 cm/10* pie plates:
Forgot to brush with milk and baked both simultaneously ~ 30 min at 220 C. Noticed afterwards someone suggesting in the comments to bake small ones 25 mins at 200 C and large ones 45 min at 200 C. Still, the cakes weren't too doughy on the inside.
I don't have much of a sweet tooth, but I ate three slices straight away. It's very buttery as one would expect. I still would like to taste the original some day, because for something as simple as this, the devil is most certainly in the details.