Preheat the oven to 175 ° (convection). Halve the marshmallows. Peel the bananas and cut in half lengthways.
Melt the butter in a non-stick pan and fry the banana halves in portions for about 3 minutes while turning. Then remove and distribute on 4 oven-safe plates. Spread the halved marshmallows on the bananas and then bake in the preheated oven for about 5 minutes until the marshmallows are golden brown.
Then take it out and serve the vanilla ice cream balls on top. Garnish with the finely chopped pistachios and chocolate sauce and serve immediately.