For the pastry, tip the flour into a large bowl and stir in 1/2 tsp salt. Grate in the cold butter and lard. Gently combine with your hands. Swiftly mix in 250ml ice-cold water using a cutlery knife. Tip the dough onto a surface and knead for 1 min until smooth. Wrap and chill for at least 1 hr.

To make the filling, heat the butter in a flameproof casserole or large frying pan over a medium-low heat and fry the onions for 10-12 mins until softened and starting to caramelise. Add the chicken and cook for 5 mins more. Stir in the korma paste, curry powder and flour, turn up the heat to medium and fry for another 2 mins. Stir in the stock gradually, in several additions, then simmer for 3 mins until the mixture has thickened. Stir in the cream and mango chutney. Leave to cool completely. Once the mixture is completely cool, cover and chill for at least 3 hrs or overnight.

Line two baking sheets with baking parchment. Divide the chilled pastry into six pieces, weighing for accuracy, if you like. Form each piece into a ball, then roll each one out on a lightly floured surface to a 20cm circle. Working with one pastry circle at a time, spoon a sixth of the filling into the middle of the circle. Wet the edge around half the circle, then fold over to the dry edge and crimp using your fingers or a fork to seal. Repeat with the remaining filling and pastry circles, placing them on the baking sheets as you go. Chill for 1 hr.

Heat the oven to 180C/160C fan/gas 4. Brush the pasties with the beaten egg and bake for 50 mins-1 hr, or until golden. Leave to cool for 10 mins, then eat hot, or cool completely to pack for a picnic. Will keep chilled in an airtight container for up to two days.