For the almond cake with blueberries, first preheat the oven to 150°C. Grease a loaf pan (23 x 13 x 8 cm) with butter and sprinkle with breadcrumbs.
Put the butter, sugar, marzipan paste and lemon juice in the bowl of a food processor and mix until smooth. Beat in the eggs, one at a time, until fully incorporated. Sift flour, baking powder and salt over the top and mix thoroughly. The batter should be completely smooth. Pour the batter into the prepared pan, smooth the surface and bake in the preheated oven for 60 minutes.
Turn out the cake in the pan onto a cooling rack. After a few minutes, invert the pan again and let the cake cool completely.
Sprinkle blueberries with sugar and keep stirring until sugar is dissolved.
Portion cake into pieces and serve almond cake with blueberries.