Stir together the coconut icecream ingredients, pour into a freezer safe container.
Freeze for about 4 hours, or until solid, removing from the freezer to stir and break up the ice crystals every hour. If you freeze the icecream for too long, let it defrost at room temperature for about 30 minutes to become scoopable again.
Melt the coconut oil, if not already liquid.
Mix together with cacao and stevia.
Set aside (keep warm to prevent coconut oil solidifying.
Peel the bananas and slice in half lengthways.
Preheat your stovetop grill plate (or a frying pan) over medium heat. Note: you might need to use a bit of coconut oil if not using a non-stick pan.
Grill the halved bananas for 2-3 minutes, flip and grill for a further minute on the other side. The bananas should become golden brown.
Place 2 banana halves on each serving plate, top with the icecream, chocolate drizzle and chopped walnuts.