2Prepare the caramel by melting the sugar in a saucepan over medium heat until golden brown. Pour the caramel into the bottom of a 9x11 inch baking pan and spread evenly.
3In a bowl, prepare the chocolate cake mix according to package instructions, using 1.5 boxes, 4 eggs, 0.75 cup oil, and 1.5 cups water. Mix until smooth.
4Pour the cake batter over the caramel in the baking pan.
5In a blender, combine sweetened condensed milk, evaporated milk, 6 eggs, and vanilla extract. Blend until smooth.
6Gently pour the flan mixture over the cake batter in the pan.
7Cover the pan with aluminum foil. Place the pan in a larger baking dish and fill the larger dish with hot water to create a water bath.
8Bake for 1 hour and 45 minutes, or until a toothpick inserted into the cake comes out clean.
9Remove from the oven and let cool for 30 minutes before unmolding.
10Invert the chocoflan onto a serving platter, slice, and serve.