Chicken, Ham, and Tarragon Pie

The ultimate comforting supper, bursting with flavorsome vegetables and a rich herby gravy. You can either use some of the pre-frozen chicken filling , in which case thaw it, then assemble the pie and eat straight away. Alternatively, you can make the filling, let cool, and assemble the pie, then freeze the whole thing uncooked ready to defrost and bake in the oven at a later date.