A delicate, classic sponge flavoured with orange and lemon zest and baked in a ring mould. The decoration isn’t quite so traditional though: small choux buns filled with an apple-puree crème diplomat and dipped in caramel for a pretty (and crunchy) finish.
Makes: one large cake, cuts into 12
Hands-on time: 3 hours
Baking time: 1 hour, 10 minutes
Skill level: Up for a challenge
To prepare the tin:
25g unsalted butter, melted
30g caster sugar
For the sponge:
85g plain flour
6 medium eggs, at room temperature
Large pinch of salt
170g icing sugar, sifted
Finely grated zest 1 large orange
Finely grated zest 1 large unwaxed lemon
½ teaspoon yuzu powder (optional)
For the choux pastry:
65g unsalted butter, diced
¼ teaspoon salt
2 teaspoons caster sugar
125g strong white bread flour, sifted
3 medium eggs, at room temperature, beaten
For the crème diplomat:
200g green apple puree (from a pouch/foil container)
35g caster sugar
½ teaspoon vanilla bean paste
2 medium egg yolks
100ml double cream, well chilled
For the caramel:
230g caster sugar
4 tablespoons water
2 tablespoons pearl sugar, for dipping
2 tablespoons freeze-dried strawberries, for dipping
You will also need:
20cm deep-fluted ring mould or bundt tin
Electric whisk or stand mixer
2 large disposable piping bags
Large baking sheet, lined with baking paper
3mm round nozzle
Step 1 – Heat the oven to 220°C/200°C fan/425°F/Gas 7. Prepare the cake mould or tin carefully so the finished cake has a fine, crisp crust: brush the inside of the mould (including the central cone) thoroughly with melted butter. Sprinkle the sugar onto the melted butter to coat, then shake out the excess.
Step 2 – To make the whisked sponge, sift the cornflour and flour into a small bowl and set aside. Separate the eggs, putting the whites into one large bowl (or the bowl of a stand mixer) and the yolks into another. Add the salt to the egg whites then whisk (using an electric hand whisk or the whisk attachment of the mixer) until they stand in stiff peaks when the whisk is lifted. Put the bowl to one side.
Step 3 – Whisk the egg yolks (no need to wash the whisk), then add the icing sugar and whisk again until the mixture is very thick and mousse-like. The whisk should leave a distinct ribbon-like trail when lifted from the bowl. Using a large metal spoon or plastic spatula, fold in both zests and the yuzu (if using). Then very carefully and gently fold in ⅓ of the sifted flours, followed by ⅓ of the whisked egg whites. Repeat until all have been thoroughly combined – check the base of the bowl for pockets of flour. Pour the mixture into the prepared mould and spread evenly.
Step 4 – Bake the sponge in the heated oven for 5 minutes, then reduce the oven temperature to 160°C/140°C fan/325°F/Gas 3 and bake for a further 30-35 minutes until the sponge is well risen, golden and starting to shrink from the sides of the tin. A skewer inserted mid-way between the side and centre of the mould should come out clean. Leave to firm up for 5 minutes then carefully unmould onto a wire rack and leave until cold.
Step 5 – Meanwhile make the choux buns: turn up the oven to 200°C/180°C fan/400°F/Gas 6. Put the water, butter, salt and sugar into a medium-sized pan and heat gently until the butter has completely melted. Quickly bring the mixture to a boil then tip in the flour all in one go. Take the pan off the heat and beat furiously with a wooden spoon until the mixture becomes a smooth, heavy dough. Put the pan back on a low heat and beat at a more gentle pace for 1 minute, until the dough comes away from the sides of the pan to make a smooth, glossy ball. Tip the dough into a large heatproof mixing bowl and cool until barely warm.
Step 6 – Using the electric whisk (or the whisk attachment of the stand mixer), gradually beat in the eggs – beating well after each addition to make a shiny, smooth paste that’s stiff enough to pipe. Transfer the mixture to a large piping bag and snip off the tip to make a 2.5cm hole. Pipe mounds about 3cm across and 2.5cm high on the lined baking sheet, spacing them well apart to allow for rising and spreading – you’ll need about 36 buns to decorate the sponge, but make extra to allow for mistakes. Dip a finger in cold water and gently flatten any peaks, then bake in the heated oven for 25 minutes.
Step 7 – Reduce the oven temperature to 180°C/160°C fan/350°F/Gas 4. Open then quickly close the oven door to release the steam, then bake for a further 5 minutes until the pastry is crisp and golden. Turn out onto a wire rack and immediately punch a small hole in the flat base of each bun, then set upside down on the rack (so the base is on top) to cool.
Step 8 – Now make the crème diplomat: heat the apple puree in a medium-sized pan with half the sugar plus the vanilla paste. In a heatproof bowl, combine the rest of the sugar with the egg yolks and cornflour to make a smooth, thick paste. Stir in the hot puree then return the mixture to the pan and stir over a medium-low heat until the mixture comes to the boil and is very smooth and thick. Transfer to a clean heatproof bowl, leave to cool, then cover and chill thoroughly.
Step 9 – Whip the chilled cream until it stands in soft peaks, then fold into the chilled apple mixture. Spoon into a piping bag fitted with the small nozzle, and pipe the crème diplomat into each choux bun through the small hole in the base. Place the sponge on a serving platter.
Step 10 – As soon as all the buns have been filled, make the caramel: put the sugar and water into a small, heavy-based pan and set over a low heat. Leave to melt gently, occasionally brushing down the sides of the pan with cold water to dislodge any sugar crystals. Meanwhile, tip the pearl sugar and the freeze-dried strawberries into separate saucers and have to hand. As soon as the sugar mixture has completely melted, bring it to the boil and cook (without stirring) until it starts to turn an amber colour.
Step 11 – Remove the pan from the heat and, working very quickly and carefully (the caramel will burn if it touches your skin), lightly dip the rounded top and sides of each filled bun into the caramel using kitchen tongs – do not use your fingers for this. Then (still using the tongs) position the flat base of each bun on the sides of the cake – starting from the base and building up two rings of buns that stick together at the sides (you’ll need to hold the first bun in place until the second is attached – but the caramel sets pretty fast). Dip every third or fourth bun in caramel and then into either the pearl sugar or the freeze-dried strawberries before attaching to the cake. Keep the caramel warm and fluid by placing it back on the heat as it starts to firm up.
If there is any caramel remaining in the pan, use it up by making angel hair to decorate the top of the sponge: dip the prongs of a fork in the caramel, lift the fork high up out of the pan to create long, fine strands of caramel, then flick the fork over the top of the cake to criss-cross it with angel hair.
Step 12 – Once assembled, serve the sponge as soon as possible.