For the crumbles, select the currants, wash them and remove them from the panicles. Knead the flour, sugar and butter into crumbles. Carefully mix in the berries.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Grease square springform pan (24 x 24 cm; alternatively round, 26 cm Ø). Break chocolate into pieces for the dough.
Melt with 250 g butter in pieces in a saucepan at low heat.
Beat the eggs, sugar and 1 pinch of salt with the whisks of the mixer for 3-4 minutes until creamy. Remove the chocolate butter from the heat and immediately stir into the egg mixture.
Mix flour, cocoa and baking powder. Quickly stir into the chocolate-egg mixture.
Smooth the brownie dough in the mould. Spread crumbles on top. Bake in a hot oven for 15-20 minutes. Take out and let cool down. Remove from the tin and cut into pieces of approx. 4 x 4 cm.