Using a #1 (1/4-inch) star pastry tip, pierce a hole in the bottom of each puff. Gently whisk the cooled pastry cream until smooth. Fit the #1 tip into a pastry bag and inject the cream into each puff. On a plate or pedestal cake stand, arrange about 20 puffs to form a circular base, about 8 inches in diameter. Drip the chocolate sauce over them. Continue to pile up the puffs, dripping more sauce as you go.