Make the detrempe by mixing the dry ingredients with soft butter until homogenous, then add water to bring the dough together.
Chill the dough in the fridge.
Make the beurre pack by pounding cold butter flat and then bringing it back together.
Fold the butter inside the detrempe and roll out into a long rectangle.
Fold the dough like a letter in thirds, turn 90 degrees, and roll out again.
Repeat the folding and rolling process for a total of six turns and three 30-minute rests.
