Preheat oven to 200 degrees C
Combine the pecans, biscuits, sugar, cinnamon, salt and vanilla (if used)
Line a baking sheet with baking paper and place 1 phyllo sheet on top
Brush the pastry with butter, and sprinkle a quarter of the nut mixture evenly over top.
Place a sheet of pastry on top, brush with butter and top with another quarter of the nut mixture.
Repeat twice more
Top with remaining phyllo sheet, and brush with butter
Arrange the apple slices on top of the pastry, slightly overlapping and leaving a 2cm border around edges
Brush the apples with the remaining butter and sprinkle with some sugar
Bake for about 20 minutes until the phyllo is golden brown and fruit is soft
Let cool slightly and serve dusted with icing sugar