Tip the chicken into a bowl with the turmeric, ginger, cumin seeds, korma paste and pinch of salt. Mix well. Leave to marinate for a few hours, or overnight (if marinating overnight, cover and chill).
Tip the marinated chicken into a medium saucepan and pour over the coconut milk. Stir, bring to a simmer over a low heat and cook for 40 mins until very tender (it should be falling apart). Leave to cool.
Meanwhile, tip the spinach into a colander and pour over a kettleful of boiled water until wilted. Leave to cool, then squeeze out as much water as you can and roughly chop. Roughly shred the chicken into the sauce in the pan, then stir through the chopped spinach, dried mango and raisins to make a loose filling. Can be made a day ahead.
Roughly halve the puff pastry, but make sure one half is slightly bigger. Roll the smaller half out onto a floured surface to a circle about 25cm in diameter, then transfer to a baking tray. Pile the filling into the middle of the pastry circle, leaving a border around the edge. Brush the border with a little of the beaten egg. Roll out the remaining pastry half to a circle about 30cm in diameter. Drape this over the filling, pressing or crimping the edges to seal. Chill for at least 20 mins. At this stage, the pie can be covered and kept chilled overnight.
Heat the oven to 200C/180C fan/ gas 6. Gently score a criss-cross pattern over the top of the pie using a sharp knife, then brush all over with more of the beaten egg. Bake for 20 mins, then remove from the oven, brush with the rest of the egg, and sprinkle over the seed and almond mixture and a little sea salt. Bake for 20 mins more, or until the pie is deep golden and the almonds are toasted. While the pie bakes, combine the dressing ingredients.
Leave the pie to cool, then cut into wedges and serve with the yogurt dressing and some chutney, if using.