Mix curd, sugar, milk and oil well. Mix flour and baking powder. Gradually add to the egg mixture. First work into a smooth dough with the whisks, then with the dough hooks of the hand mixer.
Wash the lemon hot, rub dry and grate the peel. Squeeze the juice. Mix marzipan, egg, lemon peel and 2 tablespoons of lemon juice. Knead in chopped almonds. Sort and wash the blueberries.
Roll out the dough into a rectangle (40x25 cm) on a floured work surface. Place on a baking tray lined with baking paper. Spread the marzipan mixture in the middle of the dough sheet. Spread the berries on top.
Fold the narrow side first, then the long side over the filling. Place a rail made of multiple folded aluminium foil on each long side. Pre-bake in a preheated oven (electric: 175 °C/ gas: level 2) for 20 minutes.
Remove aluminium foil. Spread the edges of the dough with whisked egg yolk. Sprinkle almond flakes on top. Bake for another 15-20 minutes. Dust with icing sugar. Makes about 12 pieces.