Make the détrempe dough (in a mixture of flour, water, and salt, the starting point for making certain types of pastry): mix together the flour, salt, and the 15g butter in a food processor. As soon as the mix has a crumbly texture, add the water.
Spread the dough into an approximately 40x25cm rectangle between two sheets of greaseproof paper.
Leave it to rest in the refrigerator for 1 to 2 hours.
Spread the butter into an approx. 18x25cm rectangle between two sheets of greaseproof paper.Trap the butter in the dough to fully incorporate.
Fold once and let it rest for at least 45 minutes in the refrigerator. Then repeat the fold 5 more times with 45 minutes of rest between each book turn.
Roll out the puff pastry to a thickness of 2mm and cut out discs of dough 16cm in diameter. Store in the refrigerator.