How to cook
Boil a syrup from the sugar and water and leave it to cool.
Bake in a preheated 360°F (180 °C) oven until reddened. Take the cake out and while still warm, pour the cold syrup over it, leave it to soak in and cool.
Beat the softened butter with the powdered sugar and smear the resulting cream on the cake on all sides. Sprinkle with ground walnuts.