In a large mixing bowl, whip 1 cup of heavy cream until stiff peaks form. Gently fold in 8 ounces of mascarpone cheese, ½ cup of sugar, 1 teaspoon of vanilla extract, and 2 tablespoons of amaretto or rum until smooth.

Pour 1 cup of strong cold coffee into a shallow dish. Dip each ladyfinger quickly in the coffee, one second per side.

Layer half of the soaked ladyfingers at the bottom of a rectangular serving dish. Spread half of the mascarpone filling over the ladyfingers. Repeat with remaining ladyfingers and filling.

Cover with plastic wrap and refrigerate for at least 2 hours, preferably overnight.

Before serving, dust the top with cocoa powder using a fine sieve.