Vanilla Sponge Recipe

Preheat and prepare

Preheat oven to 200°C (400°F). Line a large baking sheet (about 30x40 cm / 12x16 in) with parchment paper. If you want classic finger shapes, mark 3 cm x 10 cm (1.2 x 4 in) rectangles lightly on the underside of the parchment as a guide.

Whisk eggs and sugar

In a large heatproof bowl (or stand mixer bowl), combine the whole eggs and granulated sugar. Place over a saucepan of simmering water (double-boiler) and whisk constantly until the mixture is warm to the touch and sugar is largely dissolved (about 40–45°C / 105–113°F) — roughly 2–3 minutes. Remove from heat.

Whip to ribbon stage

Using an electric mixer, beat the warmed egg-sugar mixture on high speed until it triples in volume and falls in a thick ribbon when the beaters are lifted (about 6–8 minutes). Beat in the 1 tsp vanilla extract at the end.

Incorporate dry ingredients

Sift the cake flour, cornstarch and pinch of salt together. Fold one-third of the whipped egg mixture into the dry ingredients gently to lighten, then fold in the remaining egg mixture carefully to avoid deflating the batter. Use a soft rubber spatula and fold with wide strokes.

Add butter

Gently fold the cooled melted butter into the batter in a thin stream, mixing just until incorporated and smooth. Do not overmix.

Pipe or spread

Transfer the batter to a piping bag fitted with a round 1–1.2 cm tip (or use a zip-top bag with the corner snipped). Pipe fingers about 3 cm x 10 cm following the parchment guides, leaving some space between each. Alternatively, spread the batter in a thin even layer (about 1 cm thick) and cut into fingers after baking.

Bake

Bake in the preheated oven for 7–9 minutes, or until the sponge is lightly golden and springs back when touched. For a thin layer method, check at 6–8 minutes. Avoid browning too darkly.

Cool and dust

Remove from oven and let cool on the sheet for 2 minutes, then transfer parchment with sponge to a wire rack to cool completely. If you baked a sheet, cut into finger shapes once cooled. Dust lightly with powdered sugar before assembly if desired.

Bloom gelatin (if using)

If using gelatin for a firmer mousse, sprinkle 1 tsp gelatin over 15 ml cold water and let stand 5 minutes to bloom. Warm gently (10–15 seconds) to dissolve completely — do not boil.

Dissolve espresso

In a small cup combine 2 tsp instant espresso powder with 30 ml hot water, stirring until fully dissolved. Let cool slightly.

Beat mascarpone and sugar

In a bowl, whisk the mascarpone with the caster sugar and 1 tsp vanilla until smooth and slightly loose (avoid overwhipping which can become grainy). Fold in the cooled espresso mixture until evenly combined. If using gelatin, whisk the dissolved gelatin into this mixture now.

Whip cream

In a separate chilled bowl, whip the cold heavy cream to soft–medium peaks (holds shape but still glossy).

Fold together

Fold one-third of the whipped cream into the mascarpone mixture to lighten, then fold in the remaining cream gently until uniform and airy. Do not deflate — the mousse should be smooth and spreadable.

Prepare soak

Combine the cooled brewed coffee (120 ml) with the optional marsala or coffee liqueur (20 ml) in a shallow dish. Taste and adjust ratio to preference. This will be used to lightly soak the sponge fingers.

Soak sponge fingers

Quickly dip each vanilla sponge finger into the coffee mixture for 1 second — do not soak until soggy, just enough to take on moisture and coffee flavor. Place a single layer of soaked fingers in the serving dish(s) or lay them as a base on individual plates.

Pipe or spread mousse

Spoon or pipe the mascarpone coffee mousse over the soaked sponge layer to about 1–1.5 cm thickness (or as desired). Smooth the top with a spatula.

Chill

Refrigerate assembled portions for at least 1 hour to set the mousse and allow flavors to marry. If gelatin was used, chilling will result in a firmer mousse; without gelatin, the mousse will be soft but stable.

Finish and serve

Before serving dust the top lightly with cocoa powder or grate a little dark chocolate over each portion. Optionally garnish with an extra whole sponge finger or a few coffee beans. Serve chilled.