Mix all dough ingredients just until a smooth dough forms. Wrap and chill for at least 2 hours.

Soften the cold butter by tapping with a rolling pin to keep it plastic and even in texture.

In a stand mixer with the paddle, blend butter and cocoa. Shape into a neat rectangle between two sheets of parchment, roll to 1/2 cm thick, and chill 90 minutes.

Roll the dough to a rectangle 1/2 cm thick, same width as the butter and twice the height.

Enclose the butter in the dough by folding the top and bottom flaps to the center over the butter (lock‑in).

Rotate the package 90° so the seams are on the sides.

Roll lengthwise to 1/2 cm again, keeping edges straight.

Give one single fold (letter fold, 3‑fold). For detailed visuals, see Biancolievito’s pastry school page on puff pastry.

Rotate 90° and roll to 1/2 cm; give one book fold (4‑fold).

Wrap and chill 2 hours, then repeat the same two folds (one 3‑fold + one 4‑fold). Always roll with the locked seams positioned laterally.

Rest overnight in the refrigerator to relax gluten and stabilize layers.

Roll to desired thickness, cut shapes, and chill 1 hour before baking according to your recipe.