Grease a baking tray (approx. 35 x 40 cm) and dust with flour. Drain blueberries well. Coarsely grate the marzipan.
Cream butter, marzipan, 125 g sugar and 1 pinch of salt with the whisk of the hand mixer. Stir in 6 eggs one after the other. Mix flour and baking powder and stir in briefly, alternating with the milk.
Spread the dough on the baking tray. Spread blueberries on top. Bake in the preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for about 20 minutes.
Beat 4 egg whites and 1 pinch of salt until stiff, adding 150 g sugar and vanilla sugar. Remove the cake from the oven. Spread meringue loosely on the cake. Continue baking at the same temperature for about 10 minutes.
Let it cool down. Whipped cream is delicious with it.