Melt the butter in a small saucepan and draw off the heat. Crush the biscuits to crumbs and, using a fork, stir into the butter. Blend the mixture well, then spoon into the base of a buttered
Pour the mixture into the prepared tin. Bake in the centre of a moderate oven (180°C., 350°F., Gas Mark 4) for 1–1½ hours. Turn off the oven heat and leave the cheesecake in the oven for a further 15 minutes. Then allow to cool. Loosen the sides of the cheesecake and remove from the tin for serving.