Toss the broccoli (or other veg) in olive oil and season well. Put them on a roasting tray and put in the oven for 20-25 minutes
Heat a saucepan with a little olive oil and add the chopped onion. Season a little and cook gently until softening. Add the chopped mushrooms, chicken and tarragon and cook for about 5 minutes or until the mushrooms have softened and the chicken is starting to cook through
Add the flour to the pan and whisk in the stock. Cook for 2 minutes until it starts to thicken then add 2 tbsp of the milk and cook for one more minute.
Pour the sauce into the bowl with the chicken and mushrooms then divide the mix between 4 small pie dishes
Cut a pastry lid the size of the inside of each dish and lay on top of the mushroom and chicken mixture. Brush with 1 tbsp of the milk. Run a fork around each edge to press it to the side of each pie dish and bake in the oven for 10-15 minutes until the pastry is golden and risen