• Preheat the oven to 160℃ with fan or 180℃ without fan. Line a 23cm bundt tin by brushing it with soft butter generously - making sure to get all the edges and the bottom.

Caramel layer

• Layer the dulce de Leche sauce at the bottom and spread it evenly.

Flan layer

• Add the ingredients into a blender and blend until smooth, set aside to allow the mixture to release any extra air bubbles.

Chocolate cake

• Start by creaming the butter with the castor and brown sugar using an electric beater or you can do this in a stand mixer with the paddle attachment. Beat this until pale and creamy.
• Add the eggs, 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.
• Mixing on low speed add 1/3rd of the buttermilk followed buy 1/3rd of the dry ingredients. Do this twice more until all the buttermilk and dry ingredients are incorporated. I like finishing the batter with a rubber spatula to ensure all the ingredients are mixed in well.

Assemble the cake

• Layer the chocolate cake batter on top of the dulce de Leche layer, smooth it out with the rubber spatula or the back of a spoon.
• Gently pour over the flan mixture, do this very slowly, you can also ladle it into the tin or pour it over a spoon. I like to pour it through a strainer to catch any egg bits.
• Loosely cover the tin with a layer of parchment paper and then 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 2-4cm.
• Transfer to the oven and bake for 1 hour 20 minutes. I would suggest checking 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.
• Once cooled, release the edges gently with a butter knife. Place a large plate over the tin and flip the cake confidently, you should hear a thud which means the cake has released from he tin and landed on the plate.
• Keeping the cake covered, allow it to chill in the fridge overnight for the best results before cutting.
• The next day, remove the tin and top with more dulce de Leche sauce, slice and serve.