Step 1

Combine chocolate spread and milk in a small saucepan; whisk over low heat until just combined. Cool to room temperature.

Step 2

Meanwhile, heat milk in a small saucepan until warm; whisk in malted milk powder to form a smooth paste. Stir over heat for 1 minute; refrigerate for 10 minutes or until cooled. Beat butter and sifted icing sugar in a bowl with an electric mixer until light and fluffy. Add cooled malted milk mixture; beat well until light and fluffy.

Step 3

Split cakes in half. Place one cake layer on a plate or stand. Spread with one-third of the chocolate spread mixture. Reserve half the Malted Buttercream for decorating. Spread cake layer with ½ cup of remaining Malted Buttercream. Repeat layering with cake, chocolate spread mixture and Malted Buttercream, finishing with cake. Spread a layer of remaining Malted Buttercream over top and side of cake. Refrigerate for 30 minutes or until firm.

Step 4

To decorate, spread reserved Malted Buttercream over top and side of cake. Press hazelnuts around bottom third of cake. Refrigerate for 30 minutes or until firm.

Step 5

Meanwhile, stir ganache ingredients in a small saucepan over low heat until smooth. Stand the Ganache, stirring occasionally, until cooled and the texture resembles thickened cream.

Step 6

Pour cooled Ganache over top of cake, allowing mixture to run down side. Arrange Ferrero Rochers on cake. Stand until set.