Preheat oven to 200°C/400°F. Grease oven trays; line with baking paper.
2
Beat butter, extract and sugar in a small bowl with an electric mixer until just combined. Beat in egg. Stir in sifted flours, soda and coconut, in two batches.
3
Roll 2 level teaspoons of mixture into ovals; place on trays about 5cm (2 inches) apart. Flatten slightly; use the back of a fork to roughen surface.
4
Bake biscuits about 7 minutes. Lift biscuits onto a wire rack to cool.
5
Meanwhile, make Vienna cream: Beat butter, extract and sifted icing sugar in a small bowl with an electric mixer until fluffy; beat in milk.
6
Sandwich cooled biscuits with Vienna cream and jam.