Step 1

Start with the custard for the filling, as it needs to be completely cold before you use it. Put the egg yolks, cornflour and 60g caster sugar in a medium heatproof bowl and beat using an electric mixer until pale and thickened.

Step 2

Put the seeds from the vanilla pod into a large saucepan with the 300ml milk and 200ml of the cream. Set over a low-medium heat until it starts to steam. Pour about half the hot milk into the bowl with the egg yolk mixture and whisk until combined, then pour everything back into the pan. Cook over a medium-high heat, stirring continuously, for 15 minutes or until the custard is thick enough to coat the back of a spoon. Strain into a bowl, then cover with cling film touching the surface. Leave to cool, then chill until cold.

Step 3

For the cake, heat the oven to 170°C/150°C fan/gas 3½. Put the butter and 300g of the sugar in a large mixing bowl, then beat using an electric mixer until pale and creamy. Mix in the 10 egg yolks one at a time, beating well after each addition. Sift in the flour and baking powder, then beat until combined. Finally, add the 120ml milk and beat until incorporated. Scrape the batter into the lined cake tin/roasting tin and spread out to an even layer using a spatula. Set aside.

Step 4

Make the meringue topping. In a large, very clean mixing bowl, whisk the 10 egg whites with a pinch of salt until they form soft peaks when the beaters are removed. Gradually whisk in the remaining 300g sugar to make a stiff, shiny meringue. Gently spread on top of the cake mix using a spatula, creating swirly peaks. Scatter over the flaked almonds.

Step 5

Bake the cake on the middle shelf of the oven for 35-40 minutes until the meringue is puffed and golden. (If the top darkens quickly, cover with a sheet of non-stick baking paper for the remaining bake time.) Leave to cool completely in the tin.

Step 6

Whip the remaining 100ml cream in a mixing bowl to stiff peaks, then gently whisk it into the chilled custard until combined. Carefully remove the cake using the paper and transfer to a board. Cut in half widthways with a serrated knife. Put one half of the cake, meringue-side down, on a large serving plate. Spread the filling over to make a thick, even layer. Put the other half of cake on top, this time meringue-side up. Serve straightaway, with sliced banana or fresh berries if you like.