Mix together all of the crust ingredients. Divide the mixture into the glass jars and press down firmly. Place the jars in the refrigerator while you prepare the other ingredients.
In a food processor, blend the sugar, cream cheese and avocado into a smooth purée. Warm the lime juice in the microwave. Add the gelatine leaf and mix well. Whip into the avocado mixture and pour into the glass jars. Chill in the refrigerator for at least 2 hours.
This cake keeps very well in the freezer. It can therefore be made in advance and thawed gradually in the refrigerator a few hours prior to serving.