Chocolate Tiramisu

Ingredients:

2 1/2 cups strong, brewed coffee, at room temperature
1 1/2 tablespoons instant espresso granules (not instant coffee)
5 tablespoons dark rum (I used Captain Morgan)

2 3/4 cups mascarpone, divided
4 Tablespoons PLUS 1/2 cup sugar
1 teaspoon vanilla extract
1/2 teaspoon unflavored gelatin
4 large egg yolks
2 1/2 cups chilled heavy whipping cream
6 ounces bittersweet chocolate, chopped (I used semi-sweet chocolate chips)
48 lady fingers (approx, depending on the size of your dish)

cocoa for dusting

Directions:
Stir the coffee, espresso, and rum in a wide bowl until the espresso dissolves. Set aside.
Combine the 2 cups mascarpone, 4 tablespoons sugar, and vanilla in a small bowl and whisk to blend; cover and chill.  Place one tablespoon of water in a small bowl. Sprinkle the gelatin over the water. Do not dump the gelatin in otherwise you could end up with lumps. Let stand until the gelatin softens, about 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 160° on an instant-read thermometer, This can take anywhere from 5 to 10 minutes depends on your cooker. 
Remove bowl from heat. 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 2 cups chilled cream until firm peaks form. Fold half of the cream into custard in 2 additions to make a chocolate mousse. Save the remaining whipped cream for garnish.
Spread 1/4 of chocolate mousse in bottom of the trifle dish.  For perfectly soaked ladyfinger, drop into the coffee, roll and remove within 2-3 seconds. You do not want the coffee to completely penetrate to the center of the cookie otherwise they become too soggy and your tiramisu will end up watery. Dunk ladyfingers one by one in the coffee mixture and arrange in a single layer on top of the mousse.  Top with another layer of the mousse and a layer of dipped ladyfingers.  Spread the reserved sweetened mascarpone over the top of the ladyfingers.  Continue layering with the remaining mousse, about two more layers. Add one last layer of lady fingers and then top with the remaining whipped cream.  Lightly dust with cocoa powder. Let sit for at least 8 hours in the refrigerator.