Sift the flour and salt into a bowl. Rub in the low-fat spread until the mixture resembles breadcrumbs. Add just enough cold water to bring the dough together. Shape into a disc, wrap in clingfilm and chill for 30 mins.
Preheat the oven to 190°C/fan oven 170°C/gas 5.
Heat a large, lidded, non stick frying pan, spray with the cooking spray and brown the chicken pieces. You may need to do this in batches. Remove the chicken to a plate. In the same frying pan, soften the onion for 3 mins before adding the garlic and mushrooms. Cook for a further 2 mins. Stir in the flour, sage and porcini mushrooms, then gradually blend in the wine and chicken stock. Return the chicken to the pan. Bring to the boil, season, then cover and simmer for 15 mins. Tip into a ceramic pie dish with a lip and cool for 10 mins.
Roll out the pastry to a circle slightly larger than the top of the dish. Cut a narrow strip of pastry from around the outside, brush the edge of the dish with water and press the pastry strip onto the lip of the dish. Dampen the pastry border, then lift the pastry lid into place. Press down well and trim the edges. Use a fork to stamp a pattern around the edge, and use the pastry trimmings to decorate the top.
Brush with the milk and then bake the pie for 25 mins until crisp and golden.
This recipe is taken from Weight Watcher's Seasonally Sensational, published by Simon and Schuster, RRP £20 and available from Amazon