Grease a springform pan (18 cm Ø) and dust with flour. Preheat the oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). For the dough, wash and dry the lemon, finely grate the peel.
Halve the lemon and squeeze it. Cream 175 g butter, sugar, vanilla sugar and 1 pinch of salt with the whisks of the mixer. Stir in the eggs one by one. Stir in lemon juice and zest. Mix 175 g flour and baking powder and stir in.
Fill the dough into the springform pan and smooth it down. Bake in a hot oven for about 45 minutes. Remove and let cool on a cake rack.
In the meantime, break the chocolate into pieces and melt in a hot water bath. Cover all chocolate lentils with chocolate and let them dry.
Carefully remove the cake from the springform pan and cut through horizontally twice. Spread the bottom cake layer with half of the jam. Place the middle cake base on top. Spread the rest of the jam on top and place the top cake layer on top.
Place the cake on a cake plate and chill for about 30 minutes.
For the Frosting, whip cream cheese, milk and icing sugar until creamy. Spread the Frosting all around the cake.
Open the biscuits carefully so that you get a biscuit side with cream filling and a biscuit side without filling. Place a chocolate lens as a pupil on each biscuit with cream. Press the large chocolate lenses on the large biscuits and the small ones on the small biscuits.
Always spread two biscuits as pairs of eyes on the cake. Refrigerate the cake again for about 30 minutes. Eat the biscuit remains or use them for dessert.