Preheat the oven at 350 degrees. Prepare the caramel. In a saucepan over medium heat, add sugar and a dash of water to moisten the sugar. Melt the sugar in the pan, stirring to avoid burning. Cook until sugar is golden brown in color (caramelized). Immediately, pour caramel into a lightly buttered baking dish or mold. In a blender add milks, eggs and vanilla. Blend until all ingredients are incorporated, about 2 minutes. Pour mixture over caramelized sugar. Pour boiling water into a deep pan and place mold in it. Water level should cover the mold about halfway up. Bake for about one hour. Flan is done when knife inserted comes up clean. Remove mold from roasting pan and place on a rack to cool. Run a knife around the sides of the flan to disconnect from mold. Flip over onto serving plate. The caramelized sugar will form a sauce over the Flan.