Martha Collison's chocolate broken egg cake

1. Preheat the oven to 160°C, gas mark 3 and grease 3 x deep 18cm cake tins thoroughly with butter and base line with baking parchment.

2. Put the plain flour, caster sugar, brown sugar, cocoa powder and bicarbonate of soda into a large bowl and whisk to combine. Melt the butter in a small saucepan.

3. Whisk the buttermilk and milk into the melted butter and then beat in the eggs.

4. Pour the wet mixture into the dry ingredients, whisking until a smooth batter has formed. Scrape the cake mixture into the prepared cake tins and smooth the top with a spatula.

5. Bake for 25-30 minutes in the preheated oven until risen and a skewer inserted comes out clean. Allow the cakes to cool completely before icing.

6. To make the icing, place the butter into a large bowl and beat briefly to loosen it up. Add half the icing sugar and beat with an electric whisk to combine, then add the remaining icing sugar, cocoa powder and milk and beat for 5-10 minutes until really light and fluffy.

7. Assemble the cake, with a layer of icing in between each layer of sponge, on a round cake board or small plate. Apply a thin layer of icing around the sides of the cake, keeping the top un-iced, then chill for 20-30 minutes to set.

8. Use a pestle and mortar to crush the Easter chocolates into small chunks, then tip into a large baking tray. Apply another layer of icing to the sides of the chilled cake, then place a circle of baking parchment on the top. Holding the top and bottom of the cake, roll the sides in the crushed chocolates so they stick into the edges. When you are happy with the coating, place onto a cake stand.

9. Cover the top of the cake with the remaining icing, then carefully slice the filled eggs in half and place onto the top to decorate. This cake will keep for 3-4 days once iced.