Bake cinnamon rolls as directed on package. Let rolls cool completely.
Spray griddle or 10-inch skillet with cooking spray; heat griddle to 375°F or heat skillet over medium heat. Slice each roll in half crosswise.
In shallow dish, whisk eggs, milk, 2 tablespoons of the maple syrup and the vanilla until blended. Dip each cinnamon roll slice into egg mixture, turning to coat completely. Place on griddle. Cook about 2 minutes on each side or until golden brown.
In small bowl, whisk reserved icing, the remaining 2 tablespoons maple syrup and enough warm water to create a pourable syrup consistency. Serve over French toast.