1 large angel food cake, cooled
20 large marshmallows
Scant 1/2 cup strong hot coffee
1 cup whipping cream, divided
2 tbsp. chocolate syrup
1 square semisweet chocolate, for garnish
4 toothpicks

Using an electric knife or other serrated knife, make 3 cuts in cake, so that you have four layers. Line up the 4 toothpicks in a straight row, 1 protruding from each layer. Put marshmallows and strong coffee in a small pan. Stirring constantly, melt the marshmallows incompletely over low heat. (They should be almost dissolved, in a gelatin-like mixture). Put this pan in a pan of cold water to chill quickly. The marshmallow-coffee mixture will begin to set.
Whip a little more than 1/2 of the cream into soft mounds and fold in. Place the bottom layer, cut side up, on your serving plate. Spread 1/3 of the marshmallow-coffee-cream mixture on top of the cake's bottom layer. Then replace the second-from the bottom layer, aligning the toothpicks exactly. Spread another 1/3 of the mixture on top of this layer. Repeat with the third layer, again realigning the toothpicks carefully so the cake will fit together perfectly. Replace top layer. Remove toothpicks. For the topping, whip remaining cream within an hour of serving. Fold in chocolate syrup. Spread on top of cake, allowing scattered drippings on side. Garnish top with shaved chocolate.