Step 1

Place the butter, milk, and water into a saucepan and bring to the boil. Stir to ensure the butter has completely melted

Step 2

Remove from the heat and add the sifted flour and salt all at once.

Step 3

Return to a low heat and mix vigorously until the mixtures comes together into a ball and the flour is completely combined.

Step 4

Allow to cool.

Step 5

Add the beaten egg a little at a time, mixing well after each addition to incorporate all the egg. See notes

Step 6

Add the grated cheese and mix well to combine.

Step 7

Spoon the mixture around the edge of a large pie dish.

Step 8

Preheat oven to 200°C / 400°F

Step 9

Place the chicken breasts in a saucepan and cover with cold water. Season with salt and pepper.

Step 10

Bring to the boil then turn the heat off. Put the lid on the pan and allow the chicken to stand in the water for about 10 minutes, while you prepare the rest of the ingredients.

Step 11

Saute the chopped onion in a little olive oil until translucent. Do not allow it to brown.

Step 12

Add the chopped mushrooms and allow to cook with the onions until the moisture from the onions has evapourated.

Step 13

Season with salt and pepper and stir in the mustard.

Step 14

Combine the cornflour with the cream and milk (make sure there are no lumps) and add to the mixture. Stir over a low heat until the mixture has thickened.

Step 15

Remove the chicken from the water, chop into bite-sized chunks and stir into the onion and mushroom mixture.

Step 16

Stir in the peas

Step 17

Allow to cool then spoon the mixture into the middle of the pastry in the pie dish.

Step 18

Sprinkle with a little grated cheese

Step 19

Place in a pre-heated oven and bake for approximately 35 minutes until the pastry is well risen and the cheese is melted and golden.