Combine 1 cup sugar and water in a small heavy saucepan over medium-high heat; cook until sugar dissolves. Continue cooking an additional 12 minutes or until golden. Immediately pour into 6 (6-ounce) ramekins or custard cups coated with cooking spray, tipping quickly until sugar coats bottoms of ramekins; set aside.
Heat milk over medium-high heat in a heavy saucepan to 180° or until tiny bubbles form around edge (do not boil). Remove from heat.
Combine remaining ingredients in a medium bowl; stir well. Gradually add hot milk, stirring with a whisk until blended.
Divide banana mixture evenly among ramekins. Place ramekins in a 13 x 9-inch baking pan; add hot water to baking pan to a depth of 1 inch. Bake at 350° for 50 minutes or until set. Remove from pan; let cool. Cover and refrigerate 8 hours.
Loosen edges of custards with a knife or rubber spatula. Invert ramekins onto dessert plates; garnish with mint springs, if desired.