Prepare a 9 inch square baking tin by lining it with non-stick baking paper.
Melt together the butter and golden syrup, either in the microwave or in a bain marie.
Immediately add in your chopped dark and milk chocolate, stir it to help it completely melt.
Add your broken up gluten free shortbread, raisins, cornflakes, and crushed mini eggs. Mix so everything is dispersed and well coated.
Spoon the mixture into your prepared baking tin. Press it down so its even.
Pour the melted milk chocolate over the top and spread it out. Then drizzle the white chocolate on top and swirl it around with a skewer to make a pattern.
Whilst the chocolate is still wet, cover with extra chunks of the gluten free shortbread and more mini eggs.
Allow to set in the fridge for 2-3 hours until completely firm and the chocolate has set. Remove from the tin and use a sharp knife to cut into 16 squares.