Preheat the oven to 160C/325F/Gas mark 3
Place the flour, caster sugar, salt, cinnamon and instant coffee into a medium-sized mixing bowl. Rub the butter into the flour mixture. Press the dough together and knead once or twice. Divide the dough into small balls and then roll each ball in chopped walnuts.
Place balls on an ungreased baking tray about 2.5 cm/1 inch apart. Flatten each ball using the bottom of a tablespoon dipped in sugar. Bake for 20 minutes, or until the edges are crisp and lightly browned. Cool and remove to wire rack.
