Preheat oven to 325°.
Place sugar in a medium heavy skillet over medium-high heat; cook until sugar dissolves, stirring constantly. Cook 5 minutes or until golden, stirring constantly. Immediately pour into a 9-inch round cake pan, tipping quickly until caramelized sugar coats bottom of cake pan.
Combine sweetened condensed milk and remaining 4 ingredients, stirring until smooth. Pour milk mixture over syrup in cake pan.
Place cake pan in a large shallow baking pan; add hot water to a depth of 1 inch. Bake at 325° for 35 to 40 minutes or until almost set. Remove cake pan from water, and let cool completely on a wire rack. Cover and chill at least 3 hours. Loosen edges of custard with a knife. Place a plate, upside down, on top of pan; invert flan onto plate. Drizzle any remaining caramelized syrup over custard.