Soak the porcini in boiling water for 15 minutes, then drain and chop. Melt 25g of the butter in a large saucepan and gently fry the shallots and garlic for 5 minutes until soft. Add all the mushrooms and cook over a high heat for 3-4 minutes until golden and just tender. Remove from the heat and stir in the Madeira, parsley, chestnuts, pine nuts and seasoning. Leave to cool.
Preheat the oven to 200°C, gas mark 6. Steam the spinach for 2 minutes until wilted then squeeze out any water. Melt the remaining butter. Lay a clean tea towel on the work surface. Cut the stack of pastry sheets into 6 even squares. Brush each pastry square with melted butter. Lay 6 pieces in a fanned-out circle on the tea towel. Repeat with the remaining pastry to make 6 circles.
Spread the sun-dried tomato paste over the centre of each circle, followed by some steamed spinach on top. Spoon the mushroom mixture over the spinach. Gather up the pastry edges and pinch together firmly to seal into a pouch shape.
Carefully lift the parcels onto a large baking sheet and brush with the remaining butter. Bake for 18-20 minutes or until golden. Remove from the oven then carefully tie with strips of leek like a bow.
Variation: one large strudel
If you prefer, you can make one large strudel-like parcel from the sheets of filo. Do not cut the pastry into 6, instead arrange 2 sheets of filo on the tea towel with the longest side closest to you, overlapping by 5cm. Brush sparingly with butter, then add 2 more layers of 2 sheets of filo, buttering as you go.
Arrange the filling over the pastry in the same order as above, leaving a 5cm border. Fold the shorter ends over the filling, then bring the long edges together to overlap and make a long rectangular parcel. Bake for 25-30 minutes until crisp and golden, covering loosely with foil if it browns too quickly. Serve cut into thick slices.
Our thanks to Waitrose for providing this recipe. For more festive recipes see Waitrose.com/Christmas
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