Follow these simple steps to create your own Pistachio Tiramisu:

1. Prepare the Coffee Mixture: In a bowl, combine the cooled brewed coffee and coffee liqueur (if using). Set aside.
2. Whip the Cream: In a separate bowl, whip the heavy cream until soft peaks form. Gradually add the granulated sugar and continue to whip until stiff peaks form.
3. Mix the Mascarpone: In another bowl, combine the mascarpone cheese and vanilla extract. Mix until smooth and creamy.
4. Combine Mixtures: Gently fold the whipped cream into the mascarpone mixture until fully combined. Take care not to deflate the whipped cream.
5. Dip the Ladyfingers: Quickly dip each ladyfinger into the coffee mixture, ensuring they are soaked but not soggy.
6. Layer the Ingredients: 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. Add Pistachios: Sprinkle half of the finely chopped pistachios over the mascarpone layer.
8. Repeat Layers: Add another layer of soaked ladyfingers followed by the remaining mascarpone mixture. Top with the remaining pistachios.
9. Chill: Cover the dish with plastic wrap and refrigerate for at least 4 hours, or overnight for best flavor.
10. Serve: Before serving, dust the top with cocoa powder and garnish with additional pistachios if desired.

These steps will guide you in creating an incredible Pistachio Tiramisu that is sure to impress.