Place the pears into a greased baking dish. Spoon a little jam into the centre of each pear half. Press crumble mixture evenly over the surface of the pears. Bake for 20-30 minutes or until pears are just tender and crumble golden (if the top begins to brown too much before pears tender, cover loosely with foil during cooking, it will depend on the size and ripeness of your pears).