125g butter
2 tablespoons cocoa
1 teaspoon vanilla essence
1/2 cup Chelsea White Sugar
1 egg
250g packet crushed wine biscuits
3 drops peppermint essence (optional)

Place the first 5 ingredients in a pot and bring to the boil, stirring the whole time. Remove from heat. Mix in the crushed biscuits and the peppermint essence.
Press into a 20cm square tin and refrigerate until set.