In a medium-sized skillet set over medium heat, melt the butter and brown sugar together until the mixture begins to bubble, about 3-5 minutes.
¼ cup unsalted butter, ¼ cup brown sugar
Place the banana pieces, cut-side down, into the brown sugar mixture. Cook for 30-60 seconds, until just golden. Flip and cook until golden on the other side, another 30 seconds. Add the nuts to the skillet, if using.
2 ripe bananas, ¼ cup chopped pecans or walnuts
Remove the skillet from the stovetop and increase the heat to high. Pour the rum into the skillet and return it to the stovetop. Using a long wand lighter, carefully ignite the liquid in the skillet. Allow the flames to burn and die down, then remove the skillet from the heat and sprinkle in the cinnamon and salt (if using).
3 tablespoons spiced rum, ½ teaspoon ground cinnamon, ⅛ teaspoon kosher salt
Scoop vanilla ice cream into 2 bowls, then divide the bananas and sauce between the bowls and serve immediately.
2 scoops vanilla ice cream