In large sauté pan with long handle, melt butter over medium heat. Add brown sugar, vanilla, cinnamon and nutmeg; cook until melted and bubbly (about 3 minutes).
Stir in sliced bananas; continue cooking until heated through. Add rum; ignite pan using a utility lighter or long stemmed matches. Allow to cook until flame subsides.
Scoop ice cream into dessert bowls and top with banana mixture. Garnish with whipped cream and pecans, if desired. Serve immediately.