In a shallow bowl, combine the strongly brewed coffee, 1 teaspoon vanilla, and (optional) rum. Set aside.

In the bowl of a stand mixer fitted with the whisk attachment, add the egg whites. Turn the mixer on HIGH speed, then gradually add the 1/3 cup sugar. Beat until stiff peaks, about 4-5 minutes. Transfer to a separate bowl.

After removing the beaten egg whites, add the egg yolks and remaining ¼ cup sugar to the same mixing bowl. Beat for 2-3 minutes, until fluffy and pale yellow.

Add the mascarpone cheese and remaining 1 teaspoon vanilla, then mix until smooth.

Fold in the pistachio cream until smooth.

Gently fold in the beaten egg whites with a spatula until well-combined. Be careful not to deflate any of the beaten egg whites.

Assembling in a 9x9” casserole dish, generously dredge each lady finger in the coffee mixture then place in the dish. Create a single layer on the bottom of the dish with the dipped lady fingers.

Add half of the pistachio cream mixture then spread out to an even layer with a spatula. Repeat the process of layering with the dipped ladyfingers and pistachio cream.

Garnish with the finely chopped pistachios.

Chill in the fridge uncovered for at least 1 hour to overnight. The longer is chills, the better!