In a sauce pan over medium heat, melt the sugar, stirring often with a rubber spatula or wooden spoon until sugar has melted and turned golden brown. Pour the caramel into the greased bundt pan as the first layer.
To make the chocolate cake batter, use an electric mixer to cream the butter and sugar until light and fluffy. Add egg, scrape down sides of bowl and continue mixing on low speed. Meanwhile, sift together the all purpose flour, cake flour, cocoa powder, ground cinnamon, baking powder, baking soda, and kosher salt.
Add half of the sifted dry ingredients and half of the buttermilk at a time into the creamed butter and mix until ingredients are almost combined. remove bowl and scrape the sides of the bowl down and finish folding together until homogeneous.
To make the flan mixture, use a blender to combine the cream cheese, evaporated milk, condensed milk, eggs and vanilla extract. Give it whirl for about a minute.
To assemble the cake, in the bundt pan, spread the cake batter on top of the caramel sauce as the second layer. Smooth it out with a spatula. Then, pour the flan mixture over a clean spatula so that it flows evenly onto the top of the cake batter as the third layer. Spray non-stick spray on foil and cover the cake. Place the entire covered cake into another pan that is at least four inches deep. Fill up the outer pan with either boiling or simmering water until the water reaches at least 50% of the bundt pan or higher, so that the cake can cook in a hot water bath.
Bake the cake in an oven that's been preheated to 350°F for about 1 hour and 20 minutes, checking for doneness after an hour, using the toothpick test. If the toothpick comes out clean, the cake is done. If not, then continue to bake and check with a toothpick every 5 minutes until it comes out clean. Allow the cake to cool down before turning over (about 30 minutes). Invert a large plate with a slight bowl to it over the top of the bundt pan. jiggle slightly to ensure the cake releases from the sides, then quickly but carefully flip it over. This cake is best eaten at room temperature or slightly warm. Enjoy!