Put sugar, tapioca starch, salt and egg yolks into a medium bowl and whisk until smooth; set aside.

Heat banana nectar over medium low heat in a small, heavy saucepan.

Gradually whisk in egg mixture and cook, stirring constantly, until pudding is just thick and gently bubbling. Remove from heat.

Beat egg whites in a large bowl until light and frothy.

Gradually add several tablespoons of the hot pudding to the egg whites and blend in gently, making sure not to scramble the eggs.

Return pudding to low heat and gently fold in egg white mixture.

Stir gently until mixture returns to a very slight simmer, then remove from heat, stir in vanilla and set aside.

Arrange gingersnaps in the bottom of a 1 3/4-quart baking dish, or in individual dessert dishes.

Sprinkle about 1/4 cup of the granola over the gingersnaps.

Gently fold double cream into pudding, then spoon half of the pudding over the gingersnaps and granola.

Top with the bananas and sprinkle with remaining granola and half of the chocolate.

Cover with remaining pudding and garnish with remaining chocolate.

Cover and chill completely, then serve.