- Preheat oven to 200C fan forced.
- Using a 22cm (20cm base measurement) cast iron frying pan, cut a circle from the pastry as the lids of the pie, place in freezer until ready to use.
- Heat oil and butter in the pan over medium heat, sauté the onion, carrot and tomato until soft.
- Add the chicken and flour, cook until brown. Then, add the mushrooms.
- Add mustard, crème fraiche and chicken stock and stir well.
- Add thyme, rosemary, nutmeg and then season with salt and pepper. Allow to simmer until thickened.
- Take off the heat, sprinkle with tasty cheese, salt and pepper and cover pie dish with puff pastry.
- Tuck the puff pastry around the edge, brush with egg yolk then bake for 15 minutes, or until golden and puffy.
- Remove from the oven and serve with green salad.