Peel bananas, and carefully cut in half lengthwise.

In a medium saute pan over medium heat, melt 1 tablespoon butter. Add 2 tablespoons brown sugar, and swirl until dissolved. Add 2 bananas, cut side down, and cook for about 2 minutes on each side, turning very carefully. Pouring from a measuring cup, with the pan off the heat, add 1/4 cup rum. Stand back from stove, and return pan to heat. Shake the pan, allowing rum to ignite. Let the alcohol burn off, and again shake the pan, to coat the bananas. Cook until glazed and translucent, about 1 minute longer.

Remove bananas to warm plates, divide sauce between them, and repeat with remaining 2 bananas. Garnish each banana with a little dab of cr?me fra?che or sour cream, and serve immediately.