Pre-heat the oven to 160C Fan/180C/350F/Gas Mark 4 and grease and line a 2lb loaf tin
Mix together the butter or baking spread and caster sugar for around 3 minutes until light and fluffy, ideally using an electric mixer
Add the eggs and milk, and whisk in until smooth
Whisk or fold in the self raising flour and cocoa powder gently until fully combined
Pour the mixture into the loaf tin and bake for an hour, or until a skewer inserted in the centre comes out clean. Leave to cool fully
To make the buttercream, mix together the butter, cocoa powder and icing sugar until they start to combine, then add the milk, and mix until smooth. You can add a little more milk if the buttercream is too stiff. Use an electric mixer for the best results
Put the buttercream into a piping bag and pipe it onto the loaf cake, or spread on with a spoon or spatula
Decorate with dark chocolate curls if you like. I use a potato peeler to shave a bar of dark chocolate to create the curls
Store in an airtight container in a cool place and eat within 3 days. Or you can freeze it for up to 3 months