Start by making the caramel. Combine 1 cup of granulated sugar and 1/4 cup of water in a small saucepan over medium heat. Stir until the sugar dissolves, then stop stirring. Watch as it turns golden to deep amber. Pour into a well-greased 12-cup bundt pan and let sit for 10 minutes.

Preheat the oven to 350°F and prepare a large roasting pan with about an inch of hot water for the bain-marie.

In a large mixing bowl, combine chocolate cake mix, eggs, vegetable oil, sour cream, milk, and vanilla. Beat for 2 minutes until smooth and thick. Pour over the hardened caramel in the bundt pan.

For the flan, blend cream cheese in a blender first until smooth. Add condensed milk, evaporated milk, eggs, vanilla, and salt. Blend until silky and pour gently over the cake batter. Cover with aluminum foil.

Place the foil-covered bundt pan into the roasting pan with water and bake for 50-60 minutes. A toothpick should come out clean from the cake layer after 50 minutes.

Let the chocoflan cool completely, about 1 hour. Refrigerate for at least 4 hours, preferably overnight.

Run a knife around the edges and invert onto a plate. Serve chilled.