Preheat the oven to 400 degrees F.
On a lightly floured work surface, roll the puff pastry to a thickness of 1/8-inch. Using a plate or cake pan as a guide, trim the pastry to form a 10-inch circle. Transfer pastry to a plate or small baking sheet and refrigerate while you prepare the bananas.
Place an ovenproof 10-inch saute pan over medium-low heat and add the butter to the pan. Once the butter is melted, sprinkle the sugar evenly over the bottom of the pan. Cook the butter and sugar until the butter begins to brown, about 3 minutes. Add the bananas to the pan and arrange them in a tight, even single layer. Cook the bananas without turning, for 2 minutes. Take the pan off the heat and add the rum to the pan. Raise the heat to medium-high and cook the bananas for an additional 2 minutes. Lay the cold puff pastry over the bananas and cut several slits in the pastry to allow steam to escape. Transfer the pan to the oven and bake until the puff pastry is golden and puffed, about 15 minutes.
Working very carefully, invert the tart onto a large serving plate and slice into 6 portions. Serve drizzled with the chocolate sauce and garnish with macadamia nuts.
In a medium saucepan heat the heavy cream until just about to boil. Remove the pan from the heat and add the chocolate and vanilla to the pan. Stir, using a whisk, until sauce is very smooth.
Yield: 1 1/4 cups