Prepare Chocolate Dough: In a saucepan, combine water, butter, sugar, and a pinch of salt. Heat until the butter melts and mixture begins to boil.
Add Flour and Cocoa: Remove from heat and stir in all-purpose flour and unsweetened cocoa powder until the dough forms a smooth ball and pulls away from the pan.
Cool and Add Eggs: Let the dough cool slightly. Add eggs one at a time, mixing until smooth and glossy.
Pipe the Dough: Transfer the chocolate choux dough to a piping bag and pipe into desired shapes on a parchment-lined baking tray.
Bake: Bake at 200°C (390°F) for 20–25 minutes, then reduce to 180°C (355°F) for 10–15 minutes until puffed and firm. Avoid opening the oven during baking.
Cool: Let the pastries cool completely before filling.
Fill and Top: Fill with chocolate cream, custard, or whipped cream, and optionally drizzle with melted chocolate.