To a mixing bowl add butter and condensed milk.Whisk it well.
Add sugar and vinegar.Whisk it.
Now add vanilla essence and milk.
Whisk it well, I used my hand mixer, you can use a hand whisk too.Set aside. Measure flour and keep it ready.
Now in a siever add the flour,baking powder and baking soda.Sieve it well for even mixing.
Now add this flour to the wet mixture.Whisk it until combined.
Now bring together using a spatula.Butter the cake tin and sprinkle flour, tap to remove excess and make it ready.Pour the cake batter into the tin.Spread and make it even.
Preheat oven at 180 deg C for 10mins.Bake in preheated oven for 35-40 mins.Insert a tooth pick in the center of the cake to test.If the toothpicks comes out clean then the cake is ready.