Heat a pan and add brown sugar, butter and apples. Stir until brown and caramelised.
Turn off heat and add frozen raspberries to caramelised apples. Gently stir and set aside.
Make the almond filling by mixing together softened butter, castor sugar, one egg and almond flour.
Make the walnut pastry by adding chopped cold butter to the flour and chopped walnuts and add a little sugar. Mix gently, rubbing the butter a bit between your hands. Add some cold water and make a dough using your hands. Don’t over knead.
Roll out the pastry on a well floured surface. Transfer to baking tray lined with baking paper. Spread the almond filling into the centre of the rolled out dough. Place apple-raspberry filling on top and fold up the sides.
Brush the pastry with egg wash and bake for 20 minutes on 210 degrees Celsius. Dust the pastry with icing sugar and serve once cooled a little.