Creating Pistachio Tiramisu is straightforward if you follow these simple steps:

1. Prepare the Coffee Mixture: In a bowl, combine the brewed espresso with coffee liqueur (if using). Set aside to cool.
2. Whip the Cream: In a separate mixing bowl, whip the heavy cream until soft peaks form. Gradually add the powdered sugar while continuing to whip until stiff peaks form.
3. Combine Mascarpone and Pistachios: In another bowl, gently mix the mascarpone cheese with the finely ground pistachios until well combined.
4. Fold in Whipped Cream: Carefully fold the whipped cream into the mascarpone mixture until smooth and well blended.
5. Dip Ladyfingers: Quickly dip each ladyfinger into the coffee mixture, ensuring they are soaked but not soggy.
6. Layer the Dessert: In a rectangular or square dish, arrange a layer of soaked ladyfingers at the bottom. Spread half of the mascarpone mixture over the ladyfingers.
7. Repeat Layers: Add another layer of soaked ladyfingers followed by the remaining mascarpone mixture on top.
8. Chill: Cover the dish with plastic wrap and refrigerate for a minimum of 4 hours, or overnight for the best flavor.
9. Serve: Before serving, dust the top with cocoa powder and sprinkle extra ground pistachios for garnish.

These steps will guide you in creating this incredible Pistachio Tiramisu effortlessly.