Tiramisù

In a small saucepan over medium heat, bring the 1/2 cup (4 oz./125 g) sugar and 1/3 cup (3 fl. oz./80 ml) water to a simmer and cook, stirring, until the sugar is dissolved, about 3 minutes. Remove from the heat, stir in the espresso and let cool to room temperature. Stir in the rum. Pour the espresso mixture into a wide, shallow bowl and set aside.

Select a heatproof bowl that fits snugly in the rim of a saucepan. Pour water to a depth of about 2 inches (5 cm) into the saucepan and bring to a gentle simmer. In the bowl, whisk together the remaining 1/3 cup (3 oz./90 g) sugar and the egg yolks until the sugar has dissolved and the mixture is pale yellow and creamy, about 2 minutes. Place the bowl over (but not touching) the simmering water in the pan. Using an electric mixer, beat the yolk mixture on medium speed until thick and tripled in volume, about 6 minutes. Remove the bowl from over the heat and set the yolk mixture aside to cool completely, stirring frequently as it cools.

In another bowl, beat the cream on medium-high speed until stiff peaks form.

Add the mascarpone and vanilla to the cooled yolk mixture. Beat with the mixer on medium speed just until smooth and well blended. Using a rubber spatula, fold in the whipped cream just until combined.

Working in batches, immerse 15 ladyfingers in the espresso mixture, then arrange the ladyfingers in a single layer in the bottom of a 9-inch (23-cm) square baking dish. Using the rubber spatula, evenly spread one-third of the filling over the ladyfingers. Soak another 15 ladyfingers in the espresso mixture, then place them over the filling and spread evenly with half of the remaining filling. Soak the remaining ladyfingers, place them in the pan, and top with the remaining filling, again spreading evenly. Gently tap the pan against the counter to settle the ingredients. Cover with plastic wrap and refrigerate for at least 6 hours or up to overnight.

Run a small knife around the inside edge of the pan to loosen the sides. Dust the top with cocoa powder and serve. Serves 8 to 10.

Adapted from Williams-Sonoma Dessert of the Day, by Kim Laidlaw (Weldon Owen, 2013)