Sprinkle 1 cup sugar into a medium skillet. Place pan over medium heat, and cook, shaking pan often, until sugar melts and becomes a light golden brown syrup. Quickly pour syrup into a 12-cup Bundt pan, tilting to coat bottom and sides; set aside.
Place whipping cream and vanilla in a large bowl. Process eggs and next 6 ingredients in a blender just until smooth, stopping to scrape down sides (do not over-process). Stir egg mixture into cream mixture.
Pour custard over caramelized sugar in Bundt pan, and place in a large roasting pan on oven rack. Add hot water to roasting pan to a depth of 1 inch.
Bake, uncovered, at 350° for 1 hour and 15 minutes or until a knife inserted off center comes out almost clean. Remove Bundt pan from water. Cool 1 hour on a wire rack. Cover and chill at least 8 hours.
Loosen edges of flan with a small spatula; invert onto a serving plate. Cut into serving pieces and top with sweetened whipped cream, berries, and mint, if desired.