Unfold the pastry on a lightly floured work surface and smooth out any creases or folds. Using a small knife, cut a round of dough that is about 1 inch bigger than the top of an an ovenproof 9- or 10-inch skillet. Transfer the circle to a sheet pan, prick it all over with a fork, and keep it refrigerated.
Heat the oven to 425º F degrees. Meanwhile, heat the skillet over medium-high heat and melt butter. Add the maple syrup, brown sugar and cinnamon, and bring to a boil, stirring occasionally. Let simmer for 5 minutes to thicken slightly. Turn off the heat and arrange the banana slices to cover the whole bottom of the pan.
Carefully lay the pastry circle over the bananas, pressing any extra pastry around the sides of the pan so that it comes up the wall of the pan (rather than down around the bananas). Bake for 25 minutes, or until the pastry is golden brown. Cool in the pan for at least 20 minutes and up to 1 day.
Just before serving, warm the bottom of the pan for 1 or 2 minutes on the stove over low heat to loosen the caramel. Place a serving plate over the pan and quickly flip to turn the tart out, so the bananas face up. Serve with whipped cream or ice cream.