Leave to defrost overnight in a saucepan. Before I heat it, I remove some of the sauce, add quite a bit (maybe 3 very heaped teaspoons) of cornflour. Heat, stirring constantly, until it thickens. I cut a frozen pastry sheet into quarters, cook two of the quarters, and put it on top of the meat to make a fake pie. We have this with mashed potatoes and cabbage.