Sponge Cakes (make 4 cakes)

1. Preheat oven to 180°C/160°C (fan-forced). Grease two 20cm diameter round cake pans. Line bases and sides with baking paper, extending paper 3cm above pan edges.
2. Place 4 of the eggs in a large bowl of an electric mixer. Using the whisk attachment, beat for 5-6 minutes on high speed, until very thick and pale. Add half the sugar, 1 tbsp at a time, beating between each addition. Beat in half the vanilla.
3. Sift half of each of the flours, twice onto a sheet of baking paper then sift again over egg mixture. Add 1 tbsp boiling water. Gently fold to combine. Do not stir. Divide evenly among prepared pans.
4. Bake for 20-22 minutes, or until golden brown and sponge slightly shrinks away from pan sides. Immediately turn out onto a wire rack lined with greased baking paper. Allow to cool.
5. Repeat Steps 2, 3 and 4 with remaining ingredients to make two more sponge cakes.

Icing

1. To make icing, place chocolate in a large heatproof bowl. Sit bowl over a saucepan of simmering water. Stir until melted and smooth. Remove. Cool for 10 minutes.
2. Beat butter in a large bowl of an electric mixer until pale and creamy. Add chocolate and beat until combined. Beat in milk. Gradually add cocoa and sugar, beating until smooth.

To assemble

1. Place one sponge cake onto a serving plate. Spread with ⅓ cup of the icing. Using a 9cm round cutter, cut out the centre from two of the remaining sponge cakes. Sandwich together, with ⅓ cup of the icing and place on top of sponge cake on plate. Fill hole with M&M’s.
2. Spread ⅓ cup of icing over top of cake and invert remaining sponge cake on top to enclose M&M’s. Spread remaining icing over top and side.
3. Coarsely chop ⅓ cup of M&M’s and press onto icing around the base of cake. Scatter 1-2 tbsp over the top of cake. Refrigerate until required.