YOU WILL NEED
For the sponge
4 medium free-range eggs, at room temperature
125g caster sugar
Finely grated zest of 2 unwaxed medium lemons
125g self-raising flour
50g unsalted butter, melted and cooled For the creme mousseline 600ml milk
1 vanilla pod, split open
4 large free-range eggs, plus 2 egg yolks, at room temperature
180g caster sugar
1 tbsp kirsch
150g unsalted butter, at room temperature, diced For the syrup 75g caster sugar
Juice of 2 medium lemons, strained To assemble 200g marzipan
1 x 23cm springclip cake tin or loose-based, deep round cake tin, greased, floured and base lined with baking paper
A strip of acetate to fit inside the tin
Large piping bag fitted with 2cm tube
About 600g medium strawberries
200g dark chocolate, melted
To make the sponge
Pre-heat the oven to 180°C/350°F/Gas Mark 4. Put the eggs, sugar and lemon zest into a large heatproof bowl set over a pan of simmering water.
Remove from the pan and whisk using a hand-held electric mixer until the mixture has more than doubled in volume and becomes very thick, pale and mousse-like.
To check that the mixture is at the right stage, lift the beaters from the bowl -- the mixture that falls off should leave a distinct ribbon-like trail on the surface.
Sift two-thirds of the flour into the mixture, then gently fold in with a metal spoon. Add the remaining flour and fold in gently to retain as much air as possible, but make sure all the flour is incorporated. Gently fold in the melted butter.
Pour into the tin and bake for 25-30 minutes until pale golden brown and the sides of the cake shrink away from the tin. Cool the sponge in the tin for five minutes, to allow it to firm up a bit, then carefully turn out on to a wire rack (the sponge is delicate). Leave to cool while you wash the tin.
To make the creme mousseline
Bring the milk and vanilla pod just to the boil in a wide saucepan. Remove from the heat and leave to infuse for 10 minutes. Meanwhile, whisk together the eggs, egg yolks, sugar, kirsch and cornflour in a bowl just until smooth and creamy.
Remove the vanilla pod from the milk, then pour through a sieve into the egg mixture, whisking well. Pour the mixture into the washed saucepan, set over a medium heat, and stir constantly until the mixture boils and thickens; this will take about four minutes.
It's important to keep stirring to avoid the custard going lumpy. Keep stirring for a minute over the heat to make sure the mixture will be thick enough to pipe, but take care that it doesn't catch on the bottom of the pan. Stir in the butter.
Allow to cool slightly, then pour into a shallow dish. Press a disc of dampened greaseproof paper on to the surface, to prevent a skin from forming, then chill for at least one hour until cold and set firm.
To make the syrup
Put the sugar, lemon juice plus 70ml water into a small pan and heat gently until the sugar has dissolved, then boil for two minutes. Remove from the heat and cool.
When ready to assemble the cake
Roll out the marzipan on a worktop lightly dusted with icing sugar to make a thin disc 23cm across. Keep chilled until needed.
Slice the cold sponge in half horizontally to make two thin, even discs. Place the strip of acetate around the inside of the tin so it will fit snugly between the side of the tin and the sponge (or line the tin with clingfilm or parchment-lined foil).
Set one sponge disc, cut-side up, in the tin and brush liberally with the syrup. With the back of a spoon, gently squash the edges of the cake down so that they are pushed directly against the sides of the tin.
Choose 12 strawberries of the same height and cut them vertically in half. Arrange pointed-end up on top of the sponge layer, cut side against the acetate, making sure the berries are fitting snugly next to each other.
Spoon about two-thirds of the creme mousseline into the piping bag. Pipe a spiral over the sponge base in the tin to cover completely; pipe between the strawberries to fill all the gaps. Add the remaining creme mousseline to the piping bag when there is space.
Set three to five strawberries aside for the decoration, then quarter the rest. Spread these over the creme so it makes the filling about 2.5cm higher. Pipe another spiral of creme on top of the berries and smooth level with a palette knife.
Set the other disc of sponge on top, cut-side up, and brush with the rest of the syrup. Gently press the top sponge layer down on to the creme so the assembled cake is firmly pressed against the acetate all round. Lay the marzipan disc on top, then chill well.
Make some decorations from the melted chocolate. To serve, remove the acetate-wrapped cake from the tin, then gently remove the acetate.
Set on a plate and finish with the reserved strawberries and chocolate decorations.