Place butter in 2-quart shallow casserole. Microwave at High for 55 seconds or until melted. Stir in sugar and cinnamon. Microwave at High for 30 to 45 seconds or just until hot; stir well. Gently mix in bananas; microwave at High for 1 to 2 minutes. Stir gently.

Place liqueur and rum in a 1-cup glass measure; microwave at High for 30 to 40 seconds or until warm. Quickly pour over bananas and ignite (use long match). Serve immediately over vanilla ice cream.

Yields 4 to 6 servings.