Place the pastry in the prepared tin, top with the nuts and apple slices.
Mix the sugar, butter and flour by hand until the mixture becomes crumbly, sprinkle on top of the apples.
Approx. 50 mins. in the lower half of an oven preheated to 180°C. Remove from the oven, allow to cool slightly, remove from the tin, place on a cooling rack and allow to cool completely. Serve with vanilla ice cream.