Tim tam

Method

Cream the butter and caster sugar until pale and fluffy, then beat in the egg yolk and vanilla extract. Sift together the flour, cocoa powder and salt, then fold into the wet mixture until a dough forms. Roll the dough between two sheets of baking parchment to about 3mm thickness and refrigerate for 30 minutes. Cut into finger-shaped biscuits approximately 8cm long and 2cm wide, place on lined baking trays and bake at 180C for 12-15 minutes until firm. Once cooled, melt the dark chocolate and dip each biscuit to coat completely, allowing excess to drip off. Dust lightly with cocoa powder whilst the chocolate is still wet. Melt the milk chocolate and pipe a thin line along the centre of each biscuit to create the characteristic two-stripe pattern, then allow to set completely at room temperature.