Chicken, Kale and Mushroom pot pie

This recipe is from here. It was unexpectedly brilliant and I think it is going to make it to our regular rotation of dishes. The main changes from the recipe that we made were that we made more for leftovers, we will add more cornstarch next time, since it was runny and that we will make it with more puff pastry on the top.

Ingredients

• 2 tbsp olive oil
• 2 large onion, finely chopped
• 2 Tbsp dried or frozen thyme
• 6 garlic cloves, crushed and finely chopped
• 900g chicken breasts, cut into small chunks
• 500g mushrooms (brown or white, but brown preferred for colour), sliced
• 600ml chicken stock
• 200g crème fraîche
• 2 tbsp wholegrain mustard
• 300g kale
• 4.5 tsp cornflour, mixed with 2.5 tbsp cold water
• 500g pack puff pastry, laid out in sheets and thawed
• 1 egg yolk, to glaze

Method

1. Heat oven to 200C. Heat oil at medium heat in a large vessel. Add the onion and cook for 5 mins until transparent and soft. Scatter over the thyme and garlic, and stir for a few minutes. 
2. Turn up the heat and add the chicken, frying until golden but not fully cooked. 
3. Add the mushrooms and the remaining oil and fry for a few minutes. 
4. Add the stock, crème fraîche, mustard and kale, and season well. Add the cornflour mixture and stir until thickened a little. If this doesn't thicken, add more cornstarch, this is how runny the final pie filling will be. 
5. Remove from the heat and transfer to a baking dish. Cover the top of the dish with the puff pastry lid, pressing into the sides of the dish. Bake for 40 mins until the pastry is puffed up and golden.