Prepare the Espresso SoakBrew the espresso and let it cool completely. If using Amaretto, mix it into the coffee for an extra depth of flavor.
Make the Pistachio CreamWhisk the egg whites with a pinch of salt until soft peaks form. In a separate bowl, whisk the egg yolks and sugar until pale and creamy. Add the pistachio paste and vanilla bean paste, mixing until smooth. Fold in the mascarpone and Amaretto. In another bowl, whip the thickened cream until soft peaks form, then gently fold it into the pistachio mixture. Finally, fold in the whipped egg whites for an airy texture.
Assemble the TiramisuQuickly dip each ladyfinger into the cooled espresso and arrange a layer in the base of a dish. Spread half of the pistachio cream over the ladyfingers, then drizzle with additional pistachio paste. Repeat with another layer of soaked ladyfingers and the remaining pistachio cream. Smooth the top.
Chill and GarnishCover and refrigerate for at least 6 hours (preferably overnight) to let the flavors develop. Before serving, sprinkle with toasted chopped pistachios for added texture and crunch.