Brew the coffee and pour it into a wide, shallow bowl. Add 1/4 teaspoon almond extract and the rum if using. Stir to combine and set aside.

Separate the eggs, placing the egg whites in a bowl and the egg yolks in a separate bowl.

Beat the egg whites with a stand mixer fitted with the whisk attachment, slowly adding 1/3 cup granulated sugar, until stiff, about 3 minutes. Transfer to a large bowl.

In the stand mixer, beat the egg yolks with the remaining 1/3 cup sugar until fluffy and pale yellow, about 3 minutes. Add mascarpone and mix to combine.

Add pistachio paste, vanilla extract, and almond extract to the egg yolk mixture and mix well.

Gently fold half of the egg yolk mixture into the egg whites. Fold in the remaining egg yolk mixture until homogenous.

Quickly dip lady fingers in the coffee on both sides and place them in a single layer in a 9 x 9-inch square pan.

Smooth half of the mascarpone mixture on top of the lady fingers. Repeat with another layer of dipped lady fingers and top with the remaining mascarpone.

Sprinkle finely chopped pistachios on top. Refrigerate for at least 4 hours or overnight before serving.