Place the chocolate, condensed milk, vanilla, butter and liqueur in a saucepan over low heat and stir until the chocolate is melted. Increase the heat to medium-high and simmer for 3–4 minutes or until the mixture is smooth and slightly thickened. Carefully pour the mixture into a lightly greased 16cm-square tin lined with non-stick baking paper and smooth over with the back of a spoon. Refrigerate for 2 hours or until set. Remove from the refrigerator. Using a sharp knife, cut the fudge into 4cm squares and wrap each piece in non-stick baking paper. Makes 16.
* You can also use Cointreau, Grand Marnier, triple sec or even an eau de vie to flavour the fudge for adults only.