Heat oven to 375°F. Spray insides of 4 (6-oz) custard cups with cooking spray. Place custard cups on cookie sheet with sides.
In medium bowl, mix brown sugar, butter, corn syrup, orange peel and rhubarb; divide evenly among custard cups. Top each with 1 biscuit. In small bowl, mix granulated sugar and cinnamon; sprinkle over biscuits.
Bake 25 to 28 minutes or until deep golden brown; cool 1 minute. Turn upside down onto 4 serving plates; remove custard cups. Serve warm with ice cream.