Line a 20cm/8in square baking tin with parchment paper.
Put the sugar and golden syrup into a heavy based medium or large saucepan, and stir to combine. Place the saucepan over a low heat. Once you have placed the saucepan on the heat do not stir the mixture as this will cause it to crystallise. Leave the saucepan on the heat until the sugar has dissolved and the mixture has turned a golden brown, similar to the colour of maple syrup.
Remove the pan from the heat, add the bicarbonate of soda and stir well. The mixture will fizz up when you do this but don’t worry; this reaction is what creates all of the lovely air pockets in the honeycomb. Pour the mixture into the prepared baking tin and leave it to cool and set.
Place the milk and plain chocolate into a heatproof bowl and set over a pot of gently simmering water to melt. Do not allow the bowl to come into contact with the water.
Remove the honeycomb from the tin and break into pieces, then dip each piece into the chocolate. Set aside on parchment paper until the chocolate has set.