Cut 75 g butter into pieces. Knead butter, egg, flour and icing sugar first with the dough hooks of the hand mixer, then with your hands to a smooth dough. Wrap the dough in foil and chill for about 30 minutes
Roll out the dough on a floured work surface until round (approx. 30 cm Ø). Grease a tart tin (approx. 26 cm Ø), line with the dough, press the edge. Cut off protruding edges. Chill the tart for about 15 minutes.
Prick the dough several times with a fork and line with baking paper. Pour in baking lentils and bake in the preheated oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: level 3) for approx. 20 minutes. Approx. 5 minutes before the end of the baking time, remove baking paper and lentils and finish baking. Remove the tart and let it cool down
Halve 8 lemons and squeeze them. Fill up juice with water to 500 ml. Put lemon juice, 60 g butter, vanillin sugar and 250 g sugar in a pot and bring to the boil. Mix starch and some water until smooth and stir into the juice. Let simmer for about 2 minutes while stirring. Stir egg yolks and 4 tbsp. lemon cream until smooth and stir into the rest of the cream
Remove the tarte from the mould. Add the cream to the tart and chill for 1 1/2-2 hours. Wash 2 untreated lemons hot, grate dry and cut into very thin slices. Bring 200 ml water and 150 g sugar to the boil and simmer for 2-3 minutes. Add lemon slices to the syrup and simmer gently for about 1 minute. Remove the pot from the stove and let it cool down. Before serving, drain lemon slices well and spread them on the tart
waiting time approx. 2 1/2 hours