Line the springform cake pan with baking paper.

Crush the butter biscuits into fine crumbs.

Melt the unsalted butter and stir it into the biscuit crumbs with cocoa powder, 18 g caster sugar, and sea salt.

Press the biscuit mixture firmly into the prepared cake pan.

Chill the biscuit base for 20 minutes.

Melt 150 g dark chocolate, milk chocolate, and 120 g unsalted butter until smooth.

Whisk the eggs with 140 g caster sugar until thick and pale.

Fold the melted chocolate mixture into the egg mixture.

Fold in almond meal, plain flour, sea salt, Frangelico, and crushed dark chocolate.

Bake the almond chocolate cake at 175°C / 350°F for 30 minutes.

Cool the cake completely before assembling.

Spread Nutella evenly over the chilled biscuit base.

Soak the gelatine sheets in cold water until softened.

Whisk egg yolks, 64 g caster sugar, and cornflour until smooth.

Heat the milk with vanilla essence until steaming.

Whisk the hot milk into the yolk mixture, then cook until thickened.

Stir white chocolate and softened gelatine into the hot custard until melted.

Fold dried banana, chopped banana, and whipped heavy cream into the cooled custard.

Spread the banana white chocolate cream over the Nutella layer.

Place the cooled almond chocolate cake over the banana cream and chill for 60 minutes.

Whip double cream, heavy cream, vanilla bean seeds, and icing sugar to firm peaks.

Pipe the vanilla whipped cream over the chilled cake.

Pour tempered dark chocolate over the cake to create an optional chocolate shell.

Chill the finished cake for 30 minutes before slicing.