Chocolate-Pistachio Danish

Line two large baking sheets with parchment paper; set aside.
In a small bowl, stir the pistachio paste into the Pastry Cream with a rubber spatula; set aside.
On a lightly floured work surface, roll out dough to a 17-by-13-inch rectangle, about 1/4 inch thick.
Using an offset spatula, spread the pistachio-cream mixture evenly over the dough, leaving a 1/2-inch border all around.
Brush the border with beaten egg.
Sprinkle the chocolate over the cream.
With a short side facing you, roll the dough lengthwise to form a tight log.
Smooth the log with your hands, and pat in at the ends.
Transfer log to a parchment-lined baking sheet and refrigerate until firm, about 30 minutes.
Using a sharp knife, trim the ends and then slice the log into 12 rounds.
Place the slices on the prepared baking sheets, six to a sheet.
Cover with plastic wrap, and let rest in a warm place until dough is approximately doubled in bulk, about 45 minutes.
Preheat the oven to 375F.
Brush the top and sides of each slice with beaten egg.
Bake, rotating sheets halfway through, until pastries are evenly browned, 20 to 25 minutes.
Transfer to a wire rack to cool.
Serve warm or at room temperature.
These are best eaten the same day they are made.
After the dough is rolled out to a large rectangle, it is topped with a mixture of pistachio paste and Pastry Cream, then sprinkled with chopped chocolate.
The dough is rolled into a log, chilled, and then sliced into rounds.