Grind the biscuits to make a fine powder.

Take this powder in a bowl and add powdered sugar, baking powder and butter to it. Give it a good mix.

To this add a cup of milk and mix well to get a smooth lump free batter.

Take a cake tin and grease it's sides and base well with butter. Now take some plain flour and dust it all over the tin. Remove the excess flour by holding the tin upside down.

Pour the batter into the container and tap it a few times.

Bake it in a preheated oven at 180 degrees for around 15-20 minutes.

After it's done let it cool down a bit, then demould it and top it up with some grated chocolate (optional).

Spongy and delicious cake is ready!