Chicken and wild mushroom pie

Name: Chicken and wild mushroom pie
Ingredients: 250g/9oz plain flour; 250g/9oz very cold butter, cut into small cubes; ½ tsp salt; 125ml/4fl oz ice-cold water; 25g/1oz butter; 1 banana shallot, finely chopped; 1 garlic clove, finely sliced; 2 large boneless and skinless chicken breasts, cut into 1cm/½in thick slices; 150g/5½oz mixed mushrooms, such as chanterelle, girolles and chestnut mushrooms, chestnuts cut into quarters, rest left whole; 50ml/2fl oz Madeira; 150ml/5fl oz chicken stock; 2 tbsp chopped tarragon leaves; 200ml/7fl oz double cream; 2 free-range egg yolks, lightly beaten; sea salt and freshly ground black pepper