Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, and grease and line a 9" square tin
Make one sponge at a time. Mix the butter and caster sugar in a large bowl, ideally with an electric mixer, until fluffy and pale
Add the eggs and vanilla extract, and whisk until fully incorporated
Add the self raising flour and whisk in gently until you can't see any flour anymore
Add your chosen food colouring and mix in
Pour the batter into the tin and bake for 10-15 minutes until a skewer inserted into the centre comes out clean
Remove the sponge from the tin and cool on a cooling rack
Re-line the tin with baking paper and repeat steps 2-7 for the other two sponge layers
Once all of the layers are cool, use 7cm round cookie cutter to cut 6 circles out of each sponge
Make a vanilla buttercream by mixing together the butter, icing sugar, milk and the vanilla extract. If the buttercream is too stiff, you can add a little more milk
Put the buttercream into a piping bag and pipe a ring around the edge of the bottom cake layer, then fill the centre with lemon curd
Cover with the middle cake layer and again pipe a ring around the edge of the cake, then fill the centre with lemon curd
Add the final cake layer and pipe a rosette on top, then decorate with Mini Eggs
Store leftovers in an airtight container in a cool place and eat within 3 days