Preheat oven to moderate, 180°C. Lightly grease and line 2 oven trays with baking paper.

In a large bowl, using an electric mixer, beat butter and sugar together until light and fluffy. Beat in egg.

Sift flours together and fold into creamed mixture. Turn onto a lightly floured surface. Knead lightly until smooth. Wrap in plastic wrap, chill 15 minutes.

Roll out dough between 2 sheets of baking paper until 4mm thick. Using a fluted pastry wheel. cut dough into 24 rectangles 4 x 5cm. Arrange on trays 3cm apart. Bake 10-12 minutes, until lightly golden. Cool on trays for 10 minutes, then transfer to a wire rack to cool completely.

Meanwhile, to make topping; in a small saucepan combine marshmallows and butter. Stir over a low heat until melted and smooth. Mix in icing sugar. Spread coconut on flat plate. Working quickly, spread a little icing along both sides of biscuit, leaving centre strip bare. Dip in coconut, shaking off excess. Spread warmed jam down centre strip. Repeat with remaining biscuits. Allow to set.