Whisk the egg yolks and granulated sugar together in a heatproof bowl set over a pot of simmering water. Whisk constantly for about 4 minutes until the mixture is pale, thick, and reaches 160°F (71°C). Remove from heat and let cool for 5 minutes.
Add the mascarpone cheese, pistachio paste, and vanilla extract to the egg yolk mixture. Whisk until completely smooth and no lumps remain.
In a separate bowl, beat the cold heavy cream with an electric mixer until stiff peaks form. Gently fold the whipped cream into the pistachio mascarpone mixture in two additions, being careful not to deflate it.
Combine the cooled espresso and amaretto in a shallow dish. Quickly dip each ladyfinger into the espresso mixture, about 1 second per side. Do not soak them or they will fall apart.
Arrange a single layer of dipped ladyfingers in the bottom of an 8x8 inch dish or a 9-inch round dish. Spread half of the pistachio cream evenly over the top.
Add a second layer of dipped ladyfingers, then spread the remaining pistachio cream over the top. Smooth it out with an offset spatula.
Cover with plastic wrap and refrigerate for at least 6 hours, or overnight for the best flavor and texture. Before serving, sprinkle with chopped pistachios and dust lightly with powdered sugar.