Grease a springform pan (26 cm Ø) and dust with flour. Coarsely grate marzipan. Put flour, sugar, 1 pinch of salt, marzipan, butter in flakes and egg in a bowl. First knead everything into crumbles with the dough hooks of the mixer and then briefly with your hands.
Approx. 2⁄3 Press crumbles onto the bottom of the springform pan as a cake base and sprinkle with breadcrumbs. Chill for about 30 minutes.
Sort and wash the blueberries. Mix with jam. Spread blueberries on the cake base. Sprinkle the rest of the crumbled dough over it and grate it between your fingers. Place the cake in a preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see
manufacturer) bake for about 35 minutes. Let the cake cool down on a cake rack in the form. Dust with icing sugar shortly before serving. Whipped cream tastes good with it.