Beat the butter, sugar and vanilla to a cream, add beaten egg and then fold through flour until the mixture forms a firm base.
Press into a baking-paper lined 28cm x 18cm slice tin.
Spread the jam thinly over the base.
Mix the beaten egg, coconut and sugar together in a bowl until moist and well combined.
Carefully spread the coconut topping over the jam layer, making sure you take it right to the edges.
Press down lightly with a wet hand or the back of a wet spoon.
Bake in a moderate (160 degree celcius fan-forced or 180 degree oven) for 25 minutes until golden brown.
Cool in the tin and then cut into squares and store in an air-tight container.