Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, and grease and line two 8″ cake tins (that are at least 2" deep)
Make the sponge by mixing the butter and caster sugar in a large bowl until fluffy, ideally mix using an electric mixer
Add the eggs and milk, and whisk until fully incorporated
Add the self raising flour, cocoa powder, bicarbonate of soda and baking powder and whisk in until you can't see any flour anymore
Divide the mixture between the tins, use scales for accuracy if you like
Bake them for 35-40 minutes or until a thin skewer inserted in the middle comes out clean. Leave them to fully cool either in the tins or remove from the tin and place on cooling racks
To make the buttercream mix the butter and icing sugar together. Once it starts to come together add the milk and vanilla extract, and mix until smooth. I use my electric hand whisk to do this but you can also do it by hand with a spoon. If the buttercream is too stiff then you can add a little more milk if neededc
Split the buttercream into two bowls and use the orange food colouring to colour one half of the buttercream, add a little at a time until you get the desired shade
Fill a piping bag fitted with a nozzle, with the vanilla buttercream on one side and the orange coloured buttercream on the other side
If the cakes have domed on top, level them off with a cake leveller or a serrated knife
Put one of the sponges on your plate or cake stand and pipe buttercream all over it
Add the other sponge on top and pipe the remaining buttercream on top
Decorate with the Creme Eggs, Mini Creme Eggs and sprinkles
Leftovers will keep in an airtight container in a cool place for 3 days