In a wide bowl, combine condensed milk, butter and sugar. Whisk well with a beater till light and fluffy.
Add vanilla essence, curd and milk. Mix well.
Now add the dry ingredients in two batches and keep on folding the mixture with a spatula by cut and fold method.
Now check the consistency of batter and add about 1-2 tablespoon water. Consistency of the batter should be such that it should easily drop from spatula.
Grease the cake tin with butter and line it with a parchment paper. Pour the batter into the tin. Tap 4-5 times just to level the mixture.
Preheat the oven for 10 minutes before baking at 180 degrees.
Bake for 35-40 minutes at 180 degrees. Be alert after 30 minutes. Baking time will slightly vary for each convection. Insert a toothpick or skewer in the centre. If it comes out clean, cake is ready. If not, then again bake for a few minutes.
Cover with a cloth and allow the cake to cool. Once slightly cool, invert on a plate and remove parchment paper. Be careful while unmolding the cake.