It's quite hard to think about making classic puff pastry any better. Until, that is, you add chocolate (in this case, it's in the form of rich, bittersweet cocoa powder). You'll get a mysteriously dark pastry with a sweet, crackly crust and an earthy chocolate flavor eager to be adorned with cream, fruit, cinnamon, and sugar—or simply served alongside ice cream or afternoon coffee. —Ashley Rodriguez
Combine the flour, cocoa powder, sugar, and salt in the bowl of a stand mixer fitted with a paddle attachment. Add all the butter to the bowl at once and mix for 30 seconds on low speed. You want the butter to just start to break up and incorporate into the flour. Add the cold water and mix for 15 seconds. At this point the “dough” will look shaggy, crumbly and quite dry. (If you don’t have a stand mixer, you can do this by hand. Rub the cold pieces of butter between your thumb and forefinger to partially flatten it. This helps to encourage the butter layers.)
Roughly shape the mess of “dough” into a rectangle. Fold the right third of the dough over to the center. Now fold the remaining left third over the center (kind of like you're folding a letter), so that you have a stack of three layers. Rotate the dough 90°. This was your first turn. (A bench scraper comes in handy during this process. The dough will likely fall apart at some point during the first 3 turns; when it does, simply use your hands to press the dough back together.)
Using the palm of your hands, push the dough back into a flattened rectangle and repeat the process 2 more times for a total of 3 turns. If at any point the butter gets soft or the dough becomes too difficult to work with, just place it in the fridge to rest for at least 30 minutes.
After 3 turns, wrap with plastic wrap, then let rest in the fridge for at least 30 minutes or up to 1 hour. If time is an issue, you can leave the dough overnight, well wrapped in the refrigerator—just let it rest on the counter for 10 minutes to remove the chill from the butter slightly before starting the turning process again.
Once the dough has rested, the water will have hydrated much of the flour and it should resemble a dough. Continue with 3 more turns, this time using a rolling pin. Let the dough rest again in the refrigerator for 30 minutes. At this point, your dough is ready to use!
You can use the chocolate puff pastry in any desserts or pastries where you would use regular puff pastry. Bake the cold dough in a hot oven (400° F) for the first 15 to 20 minutes, then turn down the oven to 350° F and continue to bake until the dough is set, about 15 to 20 minutes more. Brush the edges with cream or egg wash for a shine. I like to sprinkle the dough with a good bit of sugar before sending it into the oven.