First make the tart base, mixing flour, soft butter, sugar and egg until firm dough. Leave to chill for half hour before rolling the dough and forming the base in prepared tin. Blind bake for 15 minutes at 160° than bake for another 5 to 10 minutes until centre of the base is golden colour and leave to cool down. Melt butter with chocolate over bain marie, whisk eggs and sugar until thick and mix all together. Spread the mixture onto a tart base and divide cherries on top. Bake in the oven at 140° for 15 minutes and leave to cool.