Break 175 g chocolate into pieces. Melt with 125 g butter in a hot water bath. Whisk eggs. Add 150 g flour, sugar, brown sugar, 1 pinch of salt, chocolate butter, espresso powder and vanilla extract.
Mix everything briefly with the whisks of the mixer to a smooth dough.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Grease a rectangular springform pan (25 x 38 cm) and dust with flour (alternatively, line a small baking tray with baking paper).
Smooth the dough in it. Bake in a hot oven for about 25 minutes.
Break meringue into large pieces. Mix with macadamia nuts. Break 300 g chocolate into pieces. Melt with 20 g butter in a hot water bath. Mix the nut meringue mixture with the chocolate. Take the cake out of the oven.
Immediately spread the chocolate-nut meringue mixture over it. Let it cool down. Cut into approx. 2 1⁄2 x 4 cm large strips.