For the syrup, put the water and sugar in a pot on the stove. Once it reaches boiling point, add the juice and zest of the lemon and boil until thickened (until you get a sugar syrup). Leave in a cool area to cool.
Take a cake form with a hole in the middle and smear it with a little oil. Arrange the phyllo pastry sheets along the bottom, carefully wrinkle them up a little.
Put the form in the oven at 356°F (180 °C) and bake the sheets about 10 min. until golden. Take the form out and leave the sheets to cool briefly.
Pour this mixture into the form over the sheets. Put the form in a 338°F (170 °C) oven and bake until your toothpick comes out dry when you poke it.
Once ready, take it out of the oven, slide a knife carefully along the sides of the form so that the cake separates from them and pour the cold sugar syrup over it. Put in the fridge for a few hours to take in the syrup, then invert it onto a platter and remove the form.