1.Blend or process flours, sugar and butter until combined. Add egg and the water, process until mixture forms a ball; cover, refrigerate 30 minutes.
2.Meanwhile, to make coconut filling, combine the water and sugar in small saucepan, stir over heat until sugar is dissolved. Bring to a boil, boil 3 minutes without stirring; cool sugar syrup 5 minutes. Place coconut in large bowl, stir in sugar syrup, egg, butter, milk, extract and baking powder.
3.Preheat oven to 180°C/160°C fan-forced. Line 25cm x 30cm swiss roll pan with baking paper, extending paper 5cm over long sides.
4.Roll pastry between sheets of baking paper until 3mm thick and large enough to cover base of pan. Gently ease into base of pan.
5.Brush jam evenly over pastry base. Spread coconut mixture over jam.
6.Place cherry halves evenly over slice top. Bake about 35 minutes. Cool in pan; cut into squares before serving.
A hit with every coconut lover, this slice just improves with age. It can also be made as tartlets.Note