Line 20cm square cake tin with baking paper or alfoil.
Melt dark chocolate melts in a lightly heated saucepan, stirring throughout melting process.
Add peppermint essence and stir.
Spread half the mixture evenly over bottom of tin.
Set in fridge for 5 minutes.
Melt white chocolate melts the same way then stir in green food colouring.
Spread this over layer of dark chocolate and then refrigerate until set.
Spread reamaining dark chocolate over white/green chocolate and set in fridge.
Cut into pieces and store in fridge.