Chocolate Tiramisu

Stir espresso and sugar in a small bowl until sugar dissolves; set aside.
Combine 1 cup mascarpone, 2 tablespoons sugar, and vanilla in a small bowl and whisk to blend; cover and chill.
Place 1 tablespoon water in a small bowl. Sprinkle gelatin over. Let stand until gelatin softens, 10-15 minutes. Whisk the remaining sugar, yolks, 1/4 cup cream, and 1/4 cup water in a medium metal bowl to blend. Place bowl over a large saucepan of boiling water (do not let bottom of bowl touch water) and whisk constantly until custard thickens and temperature reaches 160u0b0 on an instant-read thermometer, 3-4 minutes. Remove bowl; add gelatin mixture and whisk until dissolved, 15-20 seconds. Return bowl over water, add chocolate, and whisk until almost melted, about 30 seconds.
Set bowl in a large bowl of ice water and whisk until chocolate is melted and custard is cool, 5-6 minutes. Whisk in the remaining mascarpone. In another medium bowl, beat remaining 3/4 cup chilled cream until firm peaks form. Fold cream into custard in 2 additions to make a chocolate mousse.
Spread 1/4 cup chocolate mousse in bottom of each of eight 1-cup teacups or ramekins. Dunk ladyfingers in the espresso syrup and arrange in a single layer on top of the mousse, about 2 to 3 ladyfingers per cup. Repeat layering with chocolate mousse and soaked ladyfingers. Spread 2 tablespoons mascarpone topping over ladyfingers. Garnish with chocolate shavings and serve.