Roughly chop milk chocolate.
pour the melted butter over chocolate and place in Microwave for 30 seconds.Now take it out and stir continuously until the chocolate melts completely.

Now add in 1 cup sugar and stir well until sugar dissolves

Also, add 1/4 cup curd and 1 tsp vanilla extract.stir well until the mixture turns smooth and silky.Transfer in the big pot.

Place the sieve and add in 1 1/2cup maida, 3/4 cup cocoa powder, 1 /2 tsp baking powder, 1 /4 tsp baking soda and pinch of salt salt.
mix well using cut and fold method.

Now add 1/4 cup milk and mix until the batter is a smooth thick consistency.

Transfer the cake batter into the square cake mould.bake the cake at 180°C for 30 minutes.

Remove the cake from oven. Allow it to cool down completely. Cut it into pieces.

Note :- I have taken milk chocolate, so sugar is added a little less. If you add dark chocolate, increase the amount of sugar.