Sift the flour, baking powder, baking soda and salt.

Mix the butter and sugar in the bowl of your mixer until light and pale.

Add the egg and mix at least 5 minutes. Stream in slowly the oil, followed by the buttermilk. Don’t add too much at once as it will cause the emulsion to break. It is crucial to keep the mix as smooth and emulsified as possible.

Whip the mixture for 8 minutes on medium to high speed until double in volume.

Add the banana slices and mix just until they break into smaller pieces.

Add the dry ingredients and mix on low speed just until combined.

Spread the batter in a 30x25cm tray and bake in the preheated oven at 170C for 15-20 minutes.

Cool down then cut 3 discs of 16cm diameter. Usually the third disc needs to be built up from the leftovers, but that is ok, it will hold up. Keep aside.

Hazelnut ganache:

Combine the cream and milk and warm up.

Melt the chocolate.

Pour the hot liquid over the chocolate and mix with a blender, adding the hazelnut paste and fudge sauce, as well as salt while blending.

Cover with foil and place aside.

Combine the glucose, sugar and cream in a pot and warm up.

Pour over the chocolate and cocoa powder and mix to combine.

Scale what you need and keep covered in a bowl.

Melt the chocolate then mix it with the remaining ingredients.

Keep at room temperature until needed.

Caramelize the sugar until golden brown.

Mix it with the hazelnuts then transfer on a tray lined with baking paper.

Cool down then break into small pieces in a kitchen machine.

Scale what you need and keep aside.

Bloom the gelatin in water.

Mix the egg yolk with salt and sugar, then add the cornstarch and mix well.

Blend the banana with the cream and milk then mix with the egg yolk and starch.

Transfer in a small pot and cook until the cream is stiff and shiny. It takes around 1 minute from the moment it starts to boil.

Remove from heat and add the gelatin.

Cool down in the fridge covered with foil.

Whip the heavy cream.

Mix the chilled banana cream in the bowl of your mixer until smooth and creamy again. Fold in the whipped heavy cream.

Mix all the ingredients together in a bowl.

Keep the frosting aside until needed.

Arrange all your cake components on your working table – it will be much easier to assemble the cake with everything on sight.

Line a 16cm cake ring with acetate sheets.

Place a layer of banana sponge on the bottom of the ring – usually this first layer is the one that you made out of leftovers. Press it slightly then brush it with milk.

Spoon half of the hazelnut ganache, followed by 1/3 of the hazelnut crunch.

Next layer is 1/2 of the banana cream, followed by another banana sponge, milk soak, the other half of ganache, 1/3 of crunch, the other half of banana diplomat and the final layer of banana sponge.

Brush the final sponge with milk then cover with the hazelnut frosting.

Decorate with the 1/3 of crunch you have left from assembling the layers.

Refrigerate for at least 8 hours.

Enjoy!

RECIPE