Prepare coffee and allow to cool. Whip the cream with powdered sugar and cream stiffener, then fold in the mascarpone.
Dip the ladyfingers one by one into the coffee and layer in a mold. Spread half of the mascarpone cream on top. Repeat this procedure with the remaining sponge fingers and the other half of the cream.
Finally, dust the dessert with cocoa. Leave to infuse in the refrigerator for at least 2 hours.