In a bowl, combine sugar, butter, cocoa powder, coffee and water.
Place the bowl in a microwave and heat on regular heating mode for 2 minutes. The mixture should come to a boil.
Break the biscuits into small pieces. Place them in a large bowl.
Pour the above chocolate syrup over the biscuits and stir until well coated.
Transfer the mixture onto a greased and lined 6-inch springform pan and press it to even it out. Refrigerate the biscuit cake for at least 2 hours.
Meanwhile, to make the ganache, pour some hot cream over chopped milk chocolate and mix until all the chocolate melts and you have a smooth thick ganache.
Pour the cooled ganache over the set biscuit cake and refrigerate again for 15-20 minutes or until the ganache sets completely.
Use a hot, sharp knife to cut clean slices of the cake and serve.
Recipe by Bake with Shivesh at https://bakewithshivesh.com/biscuit-cake-in-a-microwave/