Preheat oven to 180 degree C. Grease a 12 cup bundt cake pan really well with oil. Set aside.

Take milk in a jug, add in vinegar and mix well. Set aside for 5 mins.

Now i used dulce de leche, so i warmed it little in a pan till it gets spreadable. You can use caramel sauce them dont need to warm it.

Pour the sauce over the pan and set aside.

Now lets make the cake batter. Take flour, cocoa, baking soda, baking powder in a sifter and sieve it. Set aside.

Take butter, sugar in a bowl and beat till fluffy.

Add in egg and beat till fluffy.

Add in half the flour mix and half of the milk mix and mix well.

now add remaining flour and milk mix and fold gently.

Spoon this over the caramel topping and spread it evenly. Now set aside in a baking tray with high side.

Now Take eggs, condensed milk and vanilla in a blender and whip well. Add in milk and mix well. Pour this over the cake and cover the whole thing with foil.

Now pour over hot boiling water on the tray and let it come half way through the pan.

Bake this covered for 1 hour to 1 ¼ hour. Insert a tooth pick to check whether the cake is done. If the toothpick comes out clean then it is done.

Remove it from oven and let it cool down for 1 hour.

Now invert it carefully. if it is not sliding out, dip the pan in boiling water and invert it. It will melt the caramel and will slide out easily.

Now chill the cake for few hours before serving.,