Gateaux Alla Napoletana Recipe

Prepare and whip eggs

Preheat the oven to 180°C (350°F). Butter and line the bottom of two 20–22 cm (8–9 in) round cake pans, then line with parchment. In a large heatproof bowl set over (not in) a simmering pan of water (bain-marie), whisk the eggs and 200 g granulated sugar until warm to the touch (about 40–45°C). Remove from heat and continue beating with an electric mixer on high speed until the mixture triples in volume, is pale and forms a ribbon when the whisk is lifted (about 8–10 minutes).

Fold the sifted flour and cornstarch together, then gently fold a third of the flour mixture into the whipped eggs to deflate it slightly and incorporate. Continue folding in the remaining flour in two additions using a spatula, mixing with gentle strokes from bottom to top to preserve the aeration. Add the vanilla extract and a pinch of salt with the final fold.

Fold in the cooled melted butter very gently, taking care not to knock out air. Divide the batter evenly between the prepared pans and smooth the tops. Bake in the preheated oven for 20–25 minutes, or until the cakes are golden and a toothpick comes out clean. Let cakes cool in the pans for 10 minutes, then turn out onto a wire rack to cool completely.

If the tops domed, level them with a serrated knife. Once fully cooled, slice each cake horizontally to create four even layers total (two layers per cake), or cut into three layers if you prefer slightly thicker tiers.

While the cakes bake, combine the hot brewed espresso and 25 g sugar in a small saucepan over low heat just until the sugar dissolves. Remove from heat and stir in the rum if using. Cool to room temperature. This syrup will be brushed on cake layers to add moisture and coffee flavor.

In a medium saucepan, warm the milk with the split vanilla bean and its scraped seeds (or 1 tsp vanilla extract) until nearly simmering. Remove from heat and let infuse 10 minutes if using the bean, then discard the pod.

In a bowl, whisk together the egg yolks, 120 g sugar and cornstarch until smooth and pale. Temper the yolks by slowly whisking about one-third of the hot milk into the yolk mixture to raise its temperature, then pour the tempered yolks back into the saucepan with the remaining milk, whisking constantly.

Return the saucepan to medium heat and cook, whisking constantly, until the mixture thickens and comes to a gentle boil. Continue cooking 1 minute, then remove from heat. Stir in the 30 g butter until melted and smooth. Transfer the pastry cream to a shallow bowl, press plastic wrap directly on the surface to prevent a skin, and chill until cold (at least 2 hours).

Chop the dark chocolate and place it in a heatproof bowl. In a small saucepan warm 100 ml of the heavy cream (from the 400 ml) until just simmering, pour over chocolate and let sit 1 minute, then stir to make a glossy ganache. Stir in 20 g butter until smooth. Let cool to lukewarm.

In a chilled bowl, whip the remaining 300 ml heavy cream with 40 g powdered sugar to soft-medium peaks. Reserve about 150 ml whipped cream for the outer finish and keep chilled. Fold the remaining whipped cream gently into the chilled pastry cream to create a lighter filling (Crème diplomate-style).

Place the first cake layer on a serving plate or cake board. Brush a thin, even layer of the coffee syrup over the cake to moisten. Spread about one-quarter of the pastry-cream/whipped-cream filling over the layer to the edge. Repeat with the remaining layers, brushing each with syrup and spreading filling, stacking as you go. Reserve a little filling for the top if desired.

Once assembled, spread a thin crumb coat of the reserved whipped cream over the top and sides to seal crumbs. Chill the cake 20–30 minutes to set the crumb coat.

When the crumb coat is set, spread the cooled chocolate ganache over the top, letting some drip slightly over the edges if desired. Use the remaining whipped cream to pipe or spread decorative swirls on top and around the base. Sprinkle the chopped toasted nuts around the edge or over the top as a traditional Napoletana touch. Dust very lightly with confectioners' sugar just before serving if desired.

Chill the finished gateaux at least 1 hour before slicing to allow the layers to settle. Serve chilled or at cool room temperature in slices.