1.Blend contents of latte sachets with the water in small bowl.
2.Beat butter, sugar, egg and latte paste in small bowl with electric mixer until combined. Stir in sifted flours in two batches.
3.Knead dough on floured surface until smooth; roll dough between sheets of baking paper until 5mm thick. Cover; refrigerate 30 minutes.
4.Preheat oven to 180°C/160°C fan-forced. Grease oven trays; line with baking paper.
5.Using a 7.5cm square cutter, cut 30 squares. Place squares on oven trays. Stamp centre of each cookie with a floured rubber stamp.
6.Bake for 15 minutes. Cool on wire racks.