Preheat oven to 170C fan-forced and line two baking trays with baking paper.
Using an electric mixer, beat the butter and sugar together until pale and creamy then beat in the egg and vanilla.
Slowly add the flours and mix until the dough comes together and is smooth. Take it out of the bowl and form into a ball then press into a disc, wrap in plastic wrap and refrigerate for 20 minutes.
Lightly flour the bench top then roll the dough out to roughly 4mm thickness then cut into rectangles measuring about 7x4cm. Place the dough 2cm apart on the baking trays and bake for 10 minutes or until they start to turn golden.
Leave them to rest on the trays for 5 minutes before transferring to a wire rack to cool completely.
Make the Butter Cream Icing according to the instructions on the packet then using a star tip, pipe a line of icing on either side of the biscuit. Use a round tip to pipe jam down the middle then sprinkle with coconut.