Cut the bananas in half, length-wise. In a non-stick skillet, melt the butter over medium heat, and add the brown sugar. Add the banana slices, cut side up. Cook for 20 seconds, undisturbed. Add the cinnamon and rum (or orange juice). Cook for another 10 seconds, and then carefully turn. Cook for another 45-60 seconds, basting with the sauce. Divide bananas between 2 plates. Drizzle the sauce on top. Serve with vanilla ice cream, or frozen yogurt, if desired.