For filling, in a large saucepan, combine pudding mix, coffee crystals, and gelatin. Stir in milk. Cook and stir over medium heat until boiling. Remove from heat; add chocolate. Stir until chocolate is melted. Transfer to a large bowl. Cover with plastic wrap. Cool for 45 minutes.*.
Meanwhile, line a 9x5x3-inch loaf pan with waxed paper or clear plastic wrap. Line bottom and sides with split ladyfingers.
Stir filling until smooth. Cool filling. Fold in the whipped cream. Spoon half of the filling into the ladyfinger-lined loaf pan. Cover filling with a layer of ladyfingers. Repeat layers. Cover; chill at least 8 hours or up to 24 hours.
To serve, uncover loaf and invert onto serving plate. Remove waxed paper or wrap. Garnish with additional whipped cream and slivered almonds, if you like. Slice into serving-size pieces.