Stir the cooled coffee and dark rum together in a shallow bowl.

In a clean bowl, beat the pasteurized egg whites with an electric mixer until stiff peaks form. Set aside.

In a separate bowl, beat the pasteurized egg yolks, sugar, and mascarpone until smooth and creamy. Gently fold in the beaten egg whites.

Dust the bottom of a 9-inch springform pan lightly with cocoa powder.

Quickly dip each ladyfinger into the coffee mixture; do not let it become soggy. Arrange a single layer in the bottom of the pan.

Spread one-third of the mascarpone mixture over the ladyfingers and dust lightly with cocoa powder.

Repeat twice more with the dipped ladyfingers, mascarpone cream, and cocoa to create three layers.

Cover and refrigerate for at least 4 hours, preferably overnight. Dust with fresh cocoa powder before slicing and serving.