Notes: To make the chocolate curls, pull a vegetable peeler or sharp knife lengthwise down the side of a semisweet chocolate bar at room temperature. Or as an alternative to the curls, sprinkle pie with unsweetened cocoa. You can bake chocolate pastry up to 1 day before filling it; cover and let stand at room temperature. If making pie through step 3 up to 4 hours ahead, cover and chill. Top with whipped cream and chocolate curls just before serving.