For the chocolate pastry, first prepare the dough. For this, mix all the ingredients just until they are combined. Wrap the dough in plastic wrap and refrigerate.
For the filling, roughly chop the chocolate. Mix with the remaining ingredients for the filling.
Preheat the oven to 180 °C. Line a baking tray with baking paper.
Beat the egg. On a floured work surface, roll out the dough about 3-4 mm thin. Depending on the desired shape, cut out either triangles, squares or circles. Place a little filling in the center, brush the edges with the egg and fold the dough closed. Press the edges neatly.
Place the chocolate puffs on the baking sheet, brush with the egg and bake for about 20 minutes. Sugar them before serving.