Preheat oven to 180 degrees Celsius.
Mix the flour,and ground hazelnuts in a food processor. Add the maple syrup and corn oil slowly and process until the mixture resembles breadcrumbs. Add the cold water and continue to process until it forms a stiff dough ball. Place the dough in a plastic bag and refrigerate for 20 minutes. Roll out evenly and line a flan dish. Prick with a fork, cover with foil and weight with dried beans. Blind bake for 10 minutes. Remove the weights and bake for a further 10 minutes. Set aside to cool.
While the pastry is cooking, slice the apples leaving the skin on. Pile the apples into the pastry shell and top with chopped hazelnuts. Combine the cinnamon with the maple syrup and brush over the apples. Cover and bake for a further 10 - 15 minutes.
Note: To ensure it doesn't go rancid, store ground hazelnut in the fridge in an airtight container.