Begin by making the passionfruit filling by pouring the milk into a medium size saucepan with the split and scraped vanilla bean. Place the milk over a medium heat until just simmering.
Place the egg yolks into a large mixing bowl and add the sugar, flour and cornflour to the yolks. Whisk together until thick and smooth. Cut 6 passionfruit in half and scoop the pulp out into the yolk mixture. Whisk briefly to combine and set aside.
Once the milk is hot add it to the yolk mixture and whisk to combine, return the milk to the pot and place the pot back on the stovetop over medium heat whisking continually until the mixture begins to thicken.
Once thick and glossy remove the custard from the heat and pour it into a bowl and cover the surface with cling-film, set aside to cool.
For the sponge layers: using a pastry brush butter each pizza tray ensuring all the edges have a coating of butter. Dust each tray with flour and tap out the excess.
Crack the eggs for the sponge layers into the bowl of a stand mixer, add the caster sugar and beat on high speed for 8 minutes until light, fluffy and doubled in volume.
Next turn the speed down on the mixer to slow and shake the flour and cornflour into the egg mix while the mixer is running. Mix only briefly until the flour is incorporated.
Remove the whisk attachment and ladle the mixture into the pizza trays and spread the mixture out evenly over the base of the trays with the base of the ladle until all the trays are filled.
Place the sponges into a pre-heated oven combi setting 185 °C for 12 minutes. Bake the layers in batches if necessary. Once the layers are just turning golden remove from the oven and remove immediately from the tins and transfer each layer to a cooling rack to cool.
Once the layers are cool place a layer on a serving platter and spread the layer with a even coating of passionfruit custard, repeat this process with the remaining layers with exception of the top layer.
Pour the cream into the bowl of the stand mixer with a whisk attachment and beat on high speed until soft peaks form. Spread the cream over the top of the cake and garnish with some passionfruit pulp and mint leaves.