Combine granulated sugar and 3 tablespoons water in a small, heavy saucepan over medium heat; cook until sugar dissolves, stirring frequently. Continue cooking until golden (about 4 minutes). Immediately pour into 4 (6-ounce) ramekins or custard cups coated with cooking spray, tilting each cup quickly until caramelized sugar coats bottom of cup. Set aside.
Combine banana and next 6 ingredients (banana through eggs), stirring well with a whisk. Divide mixture evenly among prepared custard cups. Place cups in a 9-inch square baking pan, and add hot water to pan to a depth of 1 inch. Bake at 325° for 45 minutes or until a knife inserted in center comes out clean. Remove cups from pan. Cover and chill at least 4 hours.
Loosen the edges of custards with a knife or rubber spatula. Place a dessert plate, upside down, on top of each cup, and invert onto plates. Drizzle any of the remaining caramelized syrup over the custards. Top with toasted pecans if desired.