Preheat the oven to 180°C.
Rub flour and 75g butter until crumbs form, add water to make dough, roll out, and line a 20cm tin.
Chill the pastry for 30 minutes, blind bake with beans for 15 minutes, then bake alone for 5 minutes.
Melt 150g butter and brown sugar, stir in condensed milk, and pour into the pastry case to set.
Layer sliced bananas on caramel, top with whipped cream, and decorate with grated chocolate.
Oil a tray and dust with icing sugar and cornflour for the marshmallows.
Soak gelatine sheets in 140ml cold water.
Boil granulated sugar, glucose, and 200ml water to 127°C, then stir in soaked gelatine.
Whisk egg whites to stiff peaks, slowly pour in hot syrup, add vanilla, and whisk until thick.
Spoon marshmallow mixture into the tray and let set for 1 hour.
Cut marshmallows into squares and coat in icing sugar and cornflour.
Caramelise caster sugar in a pan, add 60ml water and baby bananas to coat.
Serve pie slices garnished with ice cream, marshmallows, caramelised bananas, and mint.