Bring a pot of water to a simmer over medium heat. Combine the egg yolks, sugar and orange zest in a large stainless steel or glass bowl. Set the bowl on top of the pot of water without letting the bowl touch the water. With a whisk or an electric hand mixer, begin whipping the yolks until foamy. Gradually pour in the cherry brandy and keep whipping until the custard has doubled in size and has thickened. Pour the custard into 4 dessert bowls or martini glasses. Refrigerate for 20 to 30 minutes to set up. To serve, top with the crushed amaretti cookies, shaved chocolate, and cherries.