Simmer chicken, stock, dairy, celery, leeks, potatoes, garlic, and ham in a saucepan for 25 minutes.
Strain the liquid into a jug and reserve 250ml for the sauce.
Melt butter in the cleaned pan and stir in flour to make a roux.
Slowly whisk the reserved poaching liquid into the roux until smooth and thick.
Season with nutmeg, parsley, and salt, then stir in the cooked chicken and vegetables.
Cool the filling for 10 minutes and preheat the oven to 220°C.
Cut the pastry to fit a 14x18cm dish leaving a 3cm border.
Line the dish rim with pastry strips and fill with the chicken mixture.
Seal the pastry lid on top, cut a 1cm vent, and brush with egg glaze.
Bake for 30 minutes until golden brown.
Grate cabbage, carrot, beetroot, onion, and radishes, then mix with mayonnaise, lemon, and chilli.
Serve the hot chicken pie alongside the chilled coleslaw.