STEP 3:
Use half of the batter to fill three 6-inch cake tins, then drizzle Nutella on top followed by the rest of the batter & another drizzle of Nutella.
STEP 6:
Use 1/4 of the buttercream to frost the 1st layer. Drizzle Nutella on top & repeat with the 2nd layer. Place 3rd layer on top and refrigerate for 30 minutes.
STEP 8:
Spread the rest of the buttercream smoothly around the cake. Drizzle Nutella on top of the the cake and top with hazelnuts, sea salt flakes & gold foil.