For the sponge:

1. Preheat the oven to 180 degrees or 160 fan. Grease and line a 20cm loose-bottomed round cake tin with parchment paper.

2. Whisk the eggs and sugar together with an electric whisk or in a stand mixer for five minutes until pale and tripled in size.

3. Fold in the flour in thirds and add the melted butter.

4. Pour the batter into the prepared cake tin and bake for 20-25 minutes until golden and a skewer inserted into the centre comes out clean. Remove from the oven and cool in the tin for fiver minutes before turning out onto a wire rack to cool completely.

5. When it is cool, chill or freeze the sponge for about an hour; this makes it easier to cut later.

For the crème diplomat:

1. In a saucepan, bring the milk and vanilla to a simmer and soak the gelatine in a small bowl of cold water.

2. Whisk the egg yolks, sugar, and cornflour together, and when the milk is hot, slowly pour onto the egg mix, whisking all the time.

3. Scrape this mix back into the saucepan over a low heat and whisk until the mixture starts to thicken and bubble.

4. Remove from the heat, squeeze the water from the gelatine leaf and add to the pan, whisking well to dissolve. Scrape into a bowl and cover with clingfilm to chill completely, about two hours.

5. Once set, whisk well until smooth and add the Kirsch or liqueur if using.

6. Fold in the whipped cream and chill until ready to use.

For the strawberry syrup:

1. Blend the strawberries until smooth then push through a sieve to retain the juice.

2. Put the strawberry juice, sugar, and water into a saucepan over a low heat and cook for two to three minutes until the sugar has dissolved.

3. Remove from the heat, add the liqueur if using, and set aside to cool.

To assemble:

1. Cut the top off the sponge to make an even surface, then cut the sponge in half again horizontally to make two even discs.

2. Place one sponge disc at the bottom of a 20cm cake tin and brush with strawberry syrup.

3. Cut the stalks off the strawberries and slice three-quarters of the strawberries in half lengthways. Cut the remaining strawberries into small cubes and set aside.

4. Arrange the halved strawberries around the outside of the sponge, cut side facing outwards.

5. Pipe or pour the crème diplomat half-way up, smoothing the cream into all the gaps between the strawberries. Sprinkle over the chopped strawberries, and pipe or spread the remaining crème diplomat on top.

6. Brush the second layer of sponge on one side with the strawberry syrup and place on top of the crème diplomat, syrup side facing down. Freeze completely for about two hours or overnight.

7. Remove the cake from the tin and leave to defrost in the fridge. Dust with icing sugar and garnish with any remaining strawberry slices to serve.