You have to use really thin and soft sheets for this type of cake.
Lay them out and separate each one. Sprinkle each on evenly with the semolina and crumbled walnuts.
Grab it with your thumb and index finger on each side and start folding it like a harmonica - the way you would fold a cloth.
Smear your tray with oil and after you've folded the sheet like a harmonica, arrange it parallel to one of the tray's sides, so that the folds are visible on top. Repeat and arrange all of the sheets this way.
Then put them to bake in a preheated oven. Once baked to a pale-golden, take it out, sprinkle with the remaining crumbled walnuts and return to the oven for a few more min.
In the meantime, beat all the ingredients for the topping and carefully pour the mixture over the baked sheets, making sure you get it in between all the folds. Put it in the oven again and bake until the mixture itself hardens.
Boil the ingredients for the syrup until it becomes a golden-yellow, thick, sugar syrup. Once the cake is cold, pour the hot syrup over it.
Wait for it to cool again and absorb the syrup itself, then serve.