1 Grease an 18cm x 28cm rectangular slice pan. Line base and two sides with baking paper, extending paper 2cm above edges.

2 Dissolve coffee in water. Cool. Beat butter and sugar in a small bowl of an electric mixer until pale and creamy. Beat in coffee mixture and vanilla bean paste. Fold in flour. Turn out onto a lightly floured bench. Knead until combined.

3 Roll out dough between two sheets of baking paper into a rectangle, to about 3cm in thickness. Remove top sheet of baking paper. Slide onto an oven tray. Freeze until firm.

4 Cook in a moderately slow oven (160C) for about 20 to 25 minutes, or until lightly browned and firm to touch. Remove and stand on tray for 5 minutes. Transfer to a wire rack to cool. Cut into 3cm pieces.

5 Combine chocolate, syrup, extra butter and liqueur in a saucepan. Stir over a low heat until chocolate is melted and mixture is smooth.

6 Arrange biscuits over base of prepared pan. Pour over chocolate mixture. Smooth over