• Preheat the oven to 160℃ with fan or 180℃ without fan. Line an 8 inch round tin by brushing it with soft butter generously – making sure to get all the edges and the bottom.

To make the caramel sauce -

• In a heavy bottom sauce pot add the sugar and place on low to medium heat. Let this cook until it starts to melt and dissolve in the heat.
• Using a wooden spoon stir it together to make sure the sugar crystals have dissolved and it sauce is smooth. It will get a light brown color, then become golden before getting an amber color. Do not touch it as it is very hot. Pour it into the lined cake tin and set aside.

To make the flan layer -

• Add the ingredients into a bowl and whisk until smooth. Set aside to allow the mixture to release any extra air bubbles.

To make the chocolate cake mixture -

• In a large mixing bowl cream the butter with the castor and brown sugar using an electric beater or you can do this with a whisk. Beat this until pale and creamy. Add the egg, vanilla and beat well.
• In another bowl stir the flour, cocoa powder, baking powder, baking soda and salt. If there are any lumps, sift them together until smooth. Add 1/2 of the dry mixture and mix, followed by the buttermilk and mix again. Finishing with the remaining dry ingredients.

Let us assemble the cake -

• Layer the chocolate cake batter at the bottom, smooth it out with the rubber spatula or the back of a spoon. Gently pour over the flan mixture through a strainer, do this very slowly, you can also ladle it into the tin or pour it over a spoon.
• Loosely cover the tin with a layer of aluminum foil. Place the tin in a larger baking tray and pour boiling hot water into the large tray, the water should come up around half way through.
• Transfer to the oven and bake for 1 hour 20 minutes. Check the cake after 1 hour, a tooth pick inserted into the cake should come out clean, if not, cover it again and bake further.
• Let the cake cool completely in the tin before flipping, around 6 hours, I like to leave it in the fridge over night.
• Once cooled, run a knife around the edges and place a large plate over the tin and flip the cake confidently, you should hear a thud which means the cake has released from the tin and landed on the plate. Slice and serve.