Heat a medium non-stick skillet over high heat. Add the butter and swirl to coat the pan. When the butter shimmers, add the bananas and the macadamias and saute, stirring, until golden brown, about 8 to 10 minutes. Deglaze the pan with the rum and then flambe the bananas and the macadamias. When the flames are extinguished remove the pan from the heat.
Place a scoop of the Brown Sugar Ice Cream in a martini glass. Coat the ice cream with the warm flambe sauce and garnish with a banana chips.
Beverage suggestion: strong coffee
Brown Sugar Ice Cream:
In non-reactive medium saucepan, combine the milk, brown sugar, vanilla bean, and heat over medium heat until scalded. Turn the heat to low and simmer until the mixture is reduced by 1/3, about 15 minutes. Remove from the heat and allow to steep at least 1 hour, refrigerated, and preferably overnight: the longer it steeps the more flavor will develop. Strain the mixture, return the milk to the saucepan, and bring just to the point of boiling.
Meanwhile, fill a medium bowl with cold water and add ice. In a non-reactive medium bowl, combine the yolks and the sugar and whisk to blend. Add 4 ounces of the scalded milk mixture to the yolk mixture, mix well, and transfer the tempered yolk mixture to the saucepan. Cook over medium heat, whisking, until thickened, about 5 minutes. Do not overcook or the eggs will scramble.
Strain the mixture into a medium bowl, and place it in the bowl of ice water to cool. When cool, add the cream, and stir to blend. Freeze in an ice cream maker following the manufacturer's instructions. Do not over harden; the ice cream should have a soft consistency. Transfer to the freezer.
After slicing the banana, peel off the rind and place the strips on a baking sheet lined with parchment paper. In a small mixing bowl, whisk the lemon juice, sugar, and water together. Brush the banana pieces with the lemon mixture. Place in a pre-heated 200-degree oven and bake for about 2 hours. As the banana pieces are heated they will darken slightly. After 2 hours, remove from the oven and let cool to allow the banana chips to become firm.