Pre-heat the oven to 160C Fan/180C/350F/Gas Mark 4 and grease and line a 2lb loaf tin
Dissolve the coffee granules into the boiling water and set aside
Mix together the butter and light brown sugar using an electric mixer or a spoon until light and fluffy
Add the coffee and eggs and whisk in until smooth
Whisk in the flour, baking powder and cocoa powder until fully combined
Pour the mixture into the loaf tin and bake for an hour and 10 minutes, or until a skewer inserted in the centre comes out clean. Leave to cool fully
To make the buttercream, use an electric mixer or a spoon to mix together the butter and icing sugar until they start to combine, then add the vanilla extract and milk, and mix until smooth. You may need more milk or you may not need it all, so add it slowly
Divide the buttercream between three bowls. Colour one with pink food colouring, one with purple food colouring and one with yellow food colouring
Spread the buttercream out onto some cling film, spread each colour out in a line directly next to the following colour
Wrap the cling film tightly around the buttercream, creating a sausage shape
Snip one end of the cling film to expose the buttercream and feed the cling film sausage into a piping bag fitted with your chosen nozzle, the snipped end first
Pipe the buttercream onto the loaf cake, or you can spread it one with a spoon adding blobs of each colour alternately
Decorate with the Mini Eggs
Store in an airtight container in a cool place and eat within 3 days