Briefly mix flour, cocoa, sugar, baking powder and milk with the whisk of the hand mixer, fold in 80 g nuts. Pour the dough into a square greased baking tin (24 x 24 cm).
Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 35 minutes, remove from oven and allow to cool. Carefully remove the cake from the tin and place it on a cake rack, let it cool down.
Lightly roast the remaining nuts in a pan without fat, sprinkle with 2 tablespoons of maple syrup. Spread the nuts over the cake and drizzle with the remaining maple syrup.