Prepare a syrup by boiling 900 grams of sugar, the water and the lemon juice for 2 minutes. Put aside. In a bowl, place the eggs, 100 grams of sugar and the vanilla flavoured sugar. Beat these ingredients vigorously with whisk, an electric mixer or an electric blender, until it becomes a foamy thick white cream.

Gently add the flour to this creamy mixture. Pour it into a buttered round cake pan and bake in a warm oven for 25 minutes until done. Remove from the oven, pour the cooled syrup over the cake, and put it back into the oven for 3 or 4 minutes. Serve when cooled.