Melt 50 g (2 oz) of the butter in a large frying pan over a medium heat. Fry the apples and toss them in the butter until soft, but not disintegrating. Add the pine kernels and stir around for a minute. Stir in the cinnamon, and after 1 minute add the sugar and lemon rind and juice. Stir the bubbling mixture until the juices have evaporated. Remove from the heat.
Melt the remaining butter and brush a large baking sheet, ideally a round pizza tin, with a little butter. Lay 2 sheets of fillo pastry overlapping on the baking sheet. Brush thinly with butter, then lay on another 2 sheets of fillo on top in the opposite direction. Continue for 3-4 more layers. Spoon the apple mixture on top in a circle. Fold the overlapping edges of the pastry over the mixture. Brush another 2 sheets with butter and lay them on top of the apples. Cover with another 2 buttered sheets in the opposite direction. Repeat with all the pastry, brushing the top sheets with butter. Press to seal in the apples and make a crinkly border, pinching with your fingers.
Bake at 200°C, 400°F, Gas Mark 6 for 35-45 minutes until the top is browned. Transfer to a serving dish. Just before serving dust with icing sugar.