How to cook
Put 2 1/2 cups (600 ml) of water and the sugar in a pot and boil. Once boiling, add the starch (dissolved in 3-4 tablespoons of cold water beforehand) in a thin trickle. Once the starch thickens enough, take it off the heat and start arranging the biscuits.
In a appropriate container, put a little starch on the bottom, then spread it all over the entire surface. Add a layer of biscuits, then starch and repeat until you run out of ingredients. Leave it to cool for at least 1 hour.
To prepare the cocoa glaze: put the butter and sugar to melt in an appropriate dish, on a not very hot stove; dissolve the cocoa in a little water and while stirring continuously add it to the butter and sugar.
Mix 1 -2 minutes and it's ready. Leave it aside the 10 minutes for it to cool. Then slowly add the cocoa glaze on the cake and spread it evenly with a spatula.
Decorate with crushed chocolate. Then leave it to cool again.