Break the dark and milk chocolate up into pieces and place them into a large saucepan with the butter and golden syrup. Place the pan over low heat and stir gently until melted.
Remove the pan from the heat and stir in the Cornflakes.
Transfer the mixture to your lined tin and press it down firmly into place.
Top with Mini Eggs, placing them strategically so you won't have to cut directly through them later (this will cause the bars to crumble).
Place the whole thing in the fridge to set for 2 hours. Then just remove it from the tin, cut it into bars and enjoy!