- 6 ounces good-quality bittersweet chocolate, roughly chopped, plus an additional small chunk (at least 1 ounce) for making chocolate shavings, for optional garnish
- 3 tablespoons unsalted butter, at room temperature
- 3 eggs, separated (you will have 1 leftover white)
- 1 cup sugar
- ¾ cup heavy cream
- ¼ cup plus 1 tablespoon Kahlua or other coffee liqueur
- 1 teaspoon pure vanilla extract
- 1 pound mascarpone cheese
- 1 cup strong, hot brewed coffee
- 1/3 cup brandy or rum, or a combination of the two
- 36 ladyfingers, purchased or homemade
- Shaved chocolate or cocoa powder, for garnish (optional)
- To make the dark chocolate mousse, melt the 6 ounces chocolate and the butter in the top of a double boiler over, but not touching, barely simmering water. Heat and stir until the chocolate is melted and smooth. Set aside until it is near room temperature but still fluid.
- Whip 3 egg yolks with 2 tablespoons of the sugar in a standing mixer using the whip attachment at medium speed until the mixture is pale and light, about 5 minutes. Fold in the cooled chocolate.
- Whip ¼ cup of the heavy cream with the 1 tablespoon Kahlua to medium peaks. Gently fold into the chocolate mixture.
- In a large, clean, dry bowl, whip 2 egg whites with 2 tablespoons of the sugar until they just begin to hold a stiff peak but are not at all dry. Gently fold into the chocolate mixture. Cover with plastic wrap and refrigerate until thickened and spreadable, at least 1 hour.
- To make the mascarpone cream, whisk together the remaining ½ cup cream, ½ cup of the sugar, and the vanilla in a medium bowl until the sugar dissolves. Add the mascarpone, whisking until the mixture is smooth and thick. Set aside. (Refrigerate if not using immediately.)
- To make the coffee syrup, stir together the coffee and brandy with the remaining ¼ cup sugar and the ¼ cup Kahlua until the sugar is completely dissolved.
- To assemble the tiramisu, put 12 ladyfingers into a small (10 by 7-inch) glass or ceramic baking dish or serving dish, cutting them as needed to (mostly) cover the bottom of the dish. Use a pastry brush to soak the ladyfingers with coffee syrup, using about one third of the syrup and painting them a couple of times as the syrup absorbs into the cookies.
- Dollop and spread half of the mascarpone cream evenly over the ladyfingers. Top with another 12 ladyfingers and brush them generously with the syrup.
- Dollop and spread all of the dark chocolate mousse evenly over the ladyfingers. Top with the final 12 ladyfingers and brush them with the remaining syrup.
- . Use a grater or sharp knife to shave about 1 ounce chocolate into small pieces. Fold the chocolate into the remaining mascarpone cream, then dollop and spread the mixture evenly over the ladyfingers to form the top layer.
- . Lightly press a piece of waxed paper over the tiramisu, then wrap the dish with plastic wrap and refrigerate for at least 2 hours or up to 2 days.
- . To serve, cut the tiramisu with a sharp knife dipped in warm water and wiped with a clean towel. Carefully lift the pieces onto dessert plates with a small, flexible spatula. Top with additional chocolate shavings or sifted cocoa, if desired.