Place peeled and cored apples in a baking dish, covered with foil, and bake for 15 minutes. Cool.
Puree the nuts, butter, sugar, cinnamon and a drizzle of walnut oil to make a paste. Fill the cored apples with this mixture.
Roll out the pastry to fit around 4 apples. Wrap and mold the pastry around the apples. The warmth of your hands will help to mold the pastry, but start off working with cold pastry.
Cut out leaves from pastry scraps and place on the top along with a piece to look like a stem.
Egg wash the apples before baking to both smooth out the surface and give a golden finish.
Bake at 350 for about 40-45 minutes or until golden and you can smell the sweet aroma of the filling.
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Notes
A butter pie crust forms easily around the apples, as will puff pastry, the trick will be to work with cold pastry to mold it around the apple.