Line a deep pie dish with pastry, reserving slightly less than half for top. Place pastry-lined pie dish into freezer whilst you prepare filling.
Preheat oven to 170ºC.
Place sugar, rhubarb, apple, vanilla and cornflour into TM bowl and cook 8 min/100°C/ Reverse/speed 1.
Pour into prepared pie dish and top with raspberries or other berries of choice.
Roll out remaining pastry and cut into even strips. Lay across pie dish in a lattice pattern and brush with egg wash.
Bake 30 minutes until pastry is golden and glossy and filling is bubbling.
Serve hot or cold with cream, ice cream or both!