Bloom the gelatin leaves in cold water for 5 min.

Heat the milk, heavy cream, and split vanilla bean in a large saucepan until steaming.

Whisk the egg yolk, sugar, and cornstarch in a mixing bowl until smooth.

Whisk half of the hot milk mixture into the egg yolk mixture to temper it.

Return the tempered mixture to the saucepan and whisk over medium heat until very thick.

Remove the custard from heat and stir in the drained gelatin leaves.

Stir the white chocolate and macadamia praline into the hot custard until melted.

Cover the macadamia mousseline and refrigerate it until cold and pipeable, about 60 min.

Heat 250 ml milk, 45 g butter, 80 g sugar, and salt in a saucepan until the butter melts.

Stir in the all-purpose flour and cook the dough for 1 min until it forms a ball.

Transfer the churro dough to a piping bag fitted with a large star piping tip.

Heat the vegetable oil in a large saucepan to 180°C / 355°F.

Pipe 10 cm spiral cones of churro dough into the hot oil.

Fry the churro cones for 3 to 4 min until deep golden and crisp.

Lift out the churro cones and drain them briefly on a serving plate.

Peel and slice the 2 bananas into thick coins.

Melt 45 g unsalted butter and 80 g caster sugar in a frying pan until amber.

Add the banana slices and cook for 2 min until glazed.

Add the dark rum and cook for 30 seconds until the alcohol aroma softens.

Transfer the chilled macadamia mousseline to a piping bag and fill each churro cone.

Spoon Nutella and caramelized bananas over the filled churro cones.

Top each serving with vanilla ice cream and crushed praline nuts, then serve immediately.