Vicky ChandlerYou can't get much easier than this chicken pie. Made using pre-rolled puff pastry, cooked chicken AND mushroom soup, it comes together for a dinner that looks like you've made incredible effort. wholegrain mustard 2 tins mushroom soup (800ml) 1 egg, beaten 20 g parsley or tarragon, finely chopped (optional) You will also need from your store-cupboard 1 tbsp. Meanwhile, in a bowl add together the soup, chicken, grain mustard and your fresh herbs if you're using. Lay your pre-rolled puff pastry over the top of the pie dish and cut around the edges, leaving 2cm hanging over.