• Make the vegan Ferrero rocher ahead of time if you plan on using them to decorate the cake.

Hazelnut sponge cake

• Preheat your oven to 180°C (356°F). Line the base of three 6" cake tins with a circle of parchment paper and spray the sides with oil spray.
• Add the hazelnuts to your food processor and blitz until finely ground. Alternatively, you can use a knife to chop them finely.
• To make the vegan "buttermilk" add the soy milk and apple cider vinegar to a jug, stir and allow to sit for 10 minutes. Add the sunflower oil and vanilla extract to the buttermilk mixture and whisk to combine.
• In a large bowl mix together the finely ground hazelnuts, flour, cornflour, brown sugar, baking powder, baking soda, and salt. Add the wet ingredients to the bowl with the dry ingredients and use a spatula to fold everything together until you have a smooth batter.
• Divide the batter into the lined cake pans and bake for 35-40 minutes. Check they are ready by inserting a skewer, it should come out clean. Allow the cakes to cool in the tins for 15-20 minutes and then carefully turn them out onto a cooling rack to cool further. Refrigerate the cakes in an airtight container until ready to use. Chilling the cakes for a few hours (or overnight) makes them easier to work with and decorate.

Chocolate frosting

• Finely chop the chocolate and set it aside in a heat-resistant bowl. Add the coconut milk to a saucepan and place it on medium heat until gently simmering.
• Pour the heated coconut milk over the chocolate and allow it to sit for 2-3 minutes uncovered, before stirring with a spatula until smooth. Whisk with an electric whisk for 2 minutes then chill for 15-20 minutes. Once chilled, place the mixture in a large bowl or stand mixer and whip for another 2 minutes.
• Add the vegan butter, one tablespoon at a time while whisking to incorporate it into the mixture until soft and fluffy. Lastly, add in the icing sugar and whisk until combined.
• Cut the domes from the tops of the hazelnut sponge cakes if there are any to get them as even as possible.
• To assemble the cake, set aside about ⅔ of the frosting for the top and sides of the cake. Add a little chocolate frosting onto your turntable to secure the cake. Place the first layer of cake and follow with a layer of chocolate frosting. Smooth out the frosting using a spatula then scatter about 2 tablespoons of the chopped roasted hazelnuts on top of the frosting. Continue this process for the second layer and top with the third hazelnut sponge.
• Use a spatula to spread the remaining frosting on top and on the sides of the cake. Use a cake scraper to smooth out the surface. Place the cake in the fridge while you prepare the chocolate glaze.

Chocolate ganache glaze

• Finely chop the chocolate and set it aside in a heat-resistant bowl. Add the coconut milk to a saucepan and place it on medium heat until gently simmering. Pour the heated coconut milk over the chocolate and allow it to sit for 2-3 minutes uncovered, before stirring with a spatula until smooth. Stir in the chocolate fudge sauce and allow the mixture to come to room temperature for about 10-15 minutes.
• To glaze the cake, first of all carefully place the cake on top of an upside-down cake tin and place it into a large bowl (this is to catch the chocolate glaze that flows over). Pour the room temperature glaze over the top of the cake and allow it to run down the sides to completely cover the cake. Use a knife to carefully mark a line around the base of the cake so that you can easily remove it from the cake tin once dry.
• Allow the glaze to set slightly for about 5 minutes so that it is no longer running down the sides of the cake. Decorate the bottom sides and top of the cake with the remaining chopped hazelnuts (and some gold leaf sheets if using). Very carefully transfer the cake to a serving plate and top with vegan ferrero rocher.

Storage

• Store the cake in an airtight container or cover with cling film and refrigerate it until a couple of hours before serving. Remove it from the fridge for about 2 hours before serving to allow the frosting to come to room temperature.