The bavarois flavours can change with the seasons. I love vanilla bavarois with raspberries folded through at the last minute. The sponge is cake-making 101. However, if you want to cheat, you can just use store-bought sponge fingers.
250g caster sugar
250g plain flour
30g unsalted butter, melted
For passionfruit bavorois
300g caster sugar
5 egg yolks
500ml strained passionfruit juice
4 leaves gelatine, softened in cold water
600ml cream (35 per cent butterfat)
To make the sponge
Preheat the oven to 180°C and grease a 23cm springform tin.
Beat the eggs and sugar in a stainless-steel bowl until pale and creamy. Place the bowl over a pot of gently simmering water and whisk for 8-10 minutes or until the mixture thickens. Remove from the heat and continue to whisk for 5 minutes.
Gently fold in the flour, then the butter. Pour into the tin and bake for 30 minutes or until a skewer stuck in the centre comes out dry. Remove the springform and place the cake on a rack to cool. Slice horizontally into 4 x 1cm layers. Trim 1 layer to fit a 20cm hoop or springform tin. (Refrigerate or freeze the rest of the cake.) Press the sponge into the tin.
To make the bavarois, beat the sugar and egg yolks in a stainless-steel bowl until white and creamy. Add the passionfruit juice and beat to incorporate. Place over a pot of gently simmering water and whisk for 10-12 minutes or until the mixture is thick, making sure the eggs don't scramble and the mixture reaches about 85°C (use a sugar thermometer). Remove from the heat.
Squeeze the excess water from the gelatine; stir it into the passionfruit custard. Place the custard over a bowl of ice and stir until it cools to room temperature.
Whip the cream to firm peaks and fold through the custard. Return to the ice. Leave for another 10 minutes, stirring from time to time, then pour over the sponge and refrigerate for at least 3 hours before serving.