Preheat oven to 325°.
Combine brown sugar and water in a small, heavy saucepan over medium-low heat, and cook until sugar dissolves and is golden (about 5 minutes), stirring frequently. Immediately pour into 2 (8-inch) cake pans, tipping quickly until caramelized sugar coats bottoms of pans.
Combine the granulated sugar and the next 5 ingredients (granulated sugar through cream cheese) in a food processor or blender, and process until smooth. Pour into a large bowl. Add milks, stirring until well-blended.
Divide mixture evenly between prepared cake pans. Place pans in a jelly-roll pan; add hot water to baking pan to a depth of 1 inch. Bake at 325° for 1 hour and 15 minutes or until a knife inserted in center comes out clean. Remove pans from water. Cover and chill 3 hours.
Loosen edges of flan with a knife or rubber spatula. Place a large plate, upside down, on top of each pan; invert onto plates. Drizzle any remaining caramelized syrup over flans. Cut each into 8 wedges. Garnish with mint leaves, if desired.