Preheat your oven to 350°F.
In the bowl of a stand mixer, sift together the flour, sugar, cocoa powder, baking soda, baking powder, and salt. Mix on low with the paddle attachment until combined. Add cubed butter and mix on low until the mixture resembles wet sand.
In a small bowl, whisk together the egg, buttermilk, milk, and vanilla. Slowly pour this into the dry mixture while mixing on low. Scrape the bowl and then beat on high for 1 minute. Set aside.
In a blender, combine all flan ingredients and blend on high for 30 seconds.
Grease a bundt pan with cooking spray. Pour in the chocolate cake batter evenly. Slowly pour the flan mixture over the batter.
Spray a sheet of foil with cooking spray and tightly cover the bundt pan.
Place the bundt pan inside a larger roasting pan. Add about 1 inch of hot water to the roasting pan to create a water bath.
Bake for 1 hour 45 minutes to 2 hours. It’s done when a toothpick inserted into the cake comes out with a few crumbs.
Remove from water bath and let cool at room temperature for at least 1 hour.
Run a knife around the edges, place a plate on top, and gently invert the Chocoflan to release it.
Drizzle with cajeta or caramel and sprinkle with chopped pecans.