Preheat the oven at 350 degrees, heat water in a tea kettle for double boiler.
Blend, condensed,milk, vanilla and banana together, set aside.
Place a round cake pan (6-8) on the stove medium heat (use a kitchen towel or a glove),add the sugar and turn the heat to low, stir the sugar, it will melt and become caramel, make sure you don't burn it, it is going to turn brown. Distribute the sugar all around the pan. Turn the heat off and add the ingredients from the blender.
In a oven proof pot (I use my old fashion granite-ware roaster)place the cake pot in the middle and add hot water to the sides to cover half of the cake pot,(double boiler) cover the larger pot with a lid
cook for one hour or until a toothpick inserted in the middle come clean. Cool first and refrigerate for a couple of hours. Use a big enough plate to flip the flan over. Add whipped cream (optional)
Are you counting calories? Use a low fat condensed milk, fat free milk, 2 eggs and two egg whites and only 1/4 cup sugar. It will taste delicious as well.