Crush the biscuits and keep them aside.

Combine sugar and cocoa powder in a separate pan.

Add water gradually and mix the syrup.

Add butter to the syrup.

Boil the mixture for about 10 mins (medium flame).

Set aside to cool slightly.

Add vanilla extract.

Now pour the syrup over the crushed biscuits and combine well.

Transfer the mixture into a greased pan.

Cover and refrigerate over night.

Add any ganache if you need.