For the dough, put the sugar, butter, flour, egg and lemon zest in a suitable bowl and make a smooth shortcrust pastry. Leave to rest in the refrigerator for at least 15 minutes. Spread the bottom of a cake springform pan (24 cm ø) with baking parchment and spread two thirds of the dough evenly on the bottom. Prick several times with a fork. Place in the cold oven and bake at 200 degrees / gas mark 3 for approx. 25 min. Allow the base to cool. In the meantime, for the filling, squeeze four or possibly five lemons and measure out 200 cc of juice. Mix eggs, sugar and juice of one lemon. Wash the last two lemons hot and cut them into very thin slices. Press the remaining dough into the pan as a rim about 5 cm high so that there is a tight connection to the pre-baked pastry base, so that the filling does not run out. Pour in the liquid lemon and egg mixture.
Spread lemon slices evenly on the surface. Carefully place the cake in the oven. After 40 min of baking, sprinkle brown sugar over the top of the cake. Bake for another ten minutes until the filling is set. Serve the lemon tart lukewarm or possibly ice cold. The cake should be baked the day before. It tastes very good when well cooled. If you want to serve the cake lukewarm, put it in the oven at 100 degrees for 10 minutes before eating.