Method

• Grease and line the base of a 23 cm x 23 cm cake tin.
• Beat the butter and sugar until they are pale and creamy and then beat in the eggs.
• Sift the flour, cocoa powder and bicarbonate of soda into a large bowl.
• Fold in half of the flour mixture into the butter mixture, fold in the milk and then the remaining flour mixture and the water.
• Place the mixture into the baking tin and put into a preheated oven at 180ºC and cook for 22 minutes, or until a skewer inserted into the centre comes out clean. Leave for 5 minutes and then turn out onto a wire rack to cool for completely.
• To make the chocolate ganache, place the chocolate into a heatproof bowl. Bring the cream to the boil in a saucepan over a medium heat. Pour the cream over the chocolate and stir with a metal spoon until melted and smooth. Leave in the fridge, stirring often, for 40 minutes until thickened slightly.
• To make the chocolate filling, beat the butter until it is pale and creamy. Gradually add the icing sugar, malted milk powder and milk until smooth and combined, then beat in the chocolate until just combined and place into an icing bag.
• Cut the cake in half across the middle and pipe the chocolate filling over the middle. Use a knife to smooth it out at the end. Sprinkle the Tim Tams over the chocolate filling and place the top onto the cake and leave in the fridge for 30 minutes to set.
• Cut the cake into 18 fingers (roughly the size of a Tim Tam) and place the pieces well apart on a wire rack and pour the ganache of the top of the cakes. Use a palette knife to spread the ganache over the top and sides of each finger to ensure they are covered.
• Set aside for 10 minutes to set.