Brew the coffee. Pour the coffee into a wide, shallow bowl and 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 the bowl of a stand mixer fit with the whisk attachment and the egg yolks in a separate bowl.

Beat the egg whites with the whisk attachment and slowly stream in 1/3 cup of the granulated sugar, beating on high speed until stiff, about 3 minutes. Transfer the egg white mixture into a large bowl.

Add the egg yolks to the stand mixer bowl with the remaining 1/3 cup sugar. Beat on high speed until fluffy and pale yellow in color, about 3 minutes. Add the mascarpone and mix to combine.

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

Use a rubber spatula to add half of the egg yolk mixture into the egg whites, gently folding to combine. Add the second half and fold until homogenous.

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

Smooth about half of the mascarpone mixture on top of the lady fingers. Repeat with another layer of lady fingers dipped in coffee. Top with the second half of the mascarpone.

Top with finely chopped pistachios. Refrigerate for at least 4 hours or overnight before serving.