How to make
Beat the butter and powdered sugar with a mixer. To them, add the cocoa and beat again. Pour in the milk, vanilla and essence. Stir with a fork.
Crumble the biscuits but leave a few large pieces. Add them to the mixture, along with the ground walnuts.
For the glaze, put the milk and sugar in a container. Add the cocoa and boil on low heat.
Add the butter as well, leave it to thicken a bit. Pour the glaze over the cake. Leave in the fridge for 4-5 hours.