It is super important while the apple crumble is baking in the oven that you lightly mix the crumble 2-3 times. This ensures that the crumble mixture is cooked well and crunchy, otherwise the top of the crumble will be well cooked (and brown) and the crumble underneath will stay soft.  You can place the ramekins on a baking tray/dish so that it is easier for you take the ramekins in and out of the oven.