Chicken, Leek (and Mushroom) Pie

I used the recipe from the Woman's Weekly Classics cookbook my mum sent me. The pie is on the front cover, and it had me at 'hello'.  This is seriously an easy recipe, doesn't take too long and easily adapted to any changes you want to make. It's quite heavy though, we don't really eat creamy foods much, but I guess every once in a while its ok....

The cookbook with the pie cover:

This is the recipe from the cook book

Ingredients:
500ml chicken stock
600g chicken breast fillets
1 tbsp olive oil
40g butter
1 large leek, sliced thinly
2 stalks celery, trimmed and chopped finely
2 tbsp plain flour
2 tsp fresh thyme leaves
125ml milk
250ml cream
2 tsp wholegrain mustard
2 sheets ready rolled shortcrust pastry
1 sheet ready rolled puff pastry
1 egg yolk

Now, I didn't have any celery or short crust, I decided to make the pie with just the top as I couldn't be bothered making the case myself (terrible I know). But I figured we didn't really need it, especially as its a pretty heavy pie! Less calories, right? Right?!
I also added about six white mushrooms thinly sliced, and I used less oil and less butter, about 1 tbsp oil, and about 25-30g butter.  We had reduced fat cream and 1% milk, but I hardly think that makes up for it! Also, the recipe has no seasoning, which I think is very necessary.

Basically, I poached three chicken breast fillets in the stock for about 10 minutes on a simmer, then let it sit for another ten minutes. After that, I removed and roughly chopped them up.  I reckon using thigh fillets would be just as good, and cheaper. Could even do a combo of them both.
I melted the butter with the olive oil and threw the leeks in, softened them, then added the flour and the thyme and continued stirring for about a minute over heat. I then added a few table spoons of the stock, and gradually added the milk and the cream. Once it thickened and close to boil, I added the mustard, stirred the chicken through and left off the heat to cool for about five minutes.
Once cooled, I stuffed the mix into a pie dish (if I used short crust pastry, it would have been blind baked first), covered with the puff pastry, whisked up an egg yolk and brushed over the top. Cut the two obligatory slits in the top of the pie, and chucked in the oven on 200°C for 20 minutes.

I scooped it out, served with a side salad of spinach greens and grape tomatoes in a raspberry vinaigrette. I think the plate looks pretty bare but it was enough food, anything additional would have been over kill. I was originally thinking green beans, but alas we don't have any of those either! Didn't matter, we didn't need them after all.

And here it is, including a close up: