Pre-heat your oven to 160C Fan/350F/Gas Mark 4, and line a cupcake tin with cupcake cases
For the cupcake sponge, mix together the butter and caster sugar, ideally using an electric mixer, until smooth and fluffy
Add the eggs and vanilla extract and whisk them in well
Then gently whisk in the self raising flour
Divide the mixture between the cupcakes cases, and bake them for 20-25 minutes or until a thin skewer inserted in the centre of the cupcakes comes out clean. Put them on a rack to cool completely
To make the chocolate buttercream, mix together the butter, icing sugar and cocoa powder. When it starts to come together, add the milk and mix until smooth. You can do this by hand, but an electric whisk or stand mixer with paddle attachment will provide the best results. If the buttercream is too stiff, you can add a little more milk
Pipe the buttercream onto each cupcake using a piping bag fitted with a grass nozzle (Wilton 233) to make a nest (watch the video to see how it's done!). Then add three different coloured mini eggs in the centre
Store in an airtight container in a cool place, eat leftovers within 3 days