Apple and Blueberry Shortcake

4 large Granny Smith apples
Grated zest 1 lemon
2 T sugar
2 T water
125 g unsalted butter
125 g caster sugar
1 egg
185 g plain flour
1 t baking powder
155 g blueberries
Sugar to sprinkle
Peel apples, remove cores, cut into 16 slices each. Put apples in saucepan with lemon, sugar, water, cover and stew over low heat 10 mins, until apples soft (not mushy), allow to cool. Cream butter and caster sugar until fluffy and smooth, add egg and mix well. Sift flour and baking powder into mixture and stir to combine. Turn onto floured surface and knead smooth, divide in two and refrigerate 30 mins. Preheat oven 180°C. Roll each half of dough into round 22cm across. Press one into 24 cm springform cake tin, spread over apple mixture, leaving small border around edge, sprinkle blueberries over, place other dough on top and press edges together. Brush with water and sprinkle with sugar, bake 35-40 mins, allow to cool in tin 20 mins then remove. Serve with whipped cream.