1/3 cup cocoa powder
1/3 cup hot water
150g 70% dark chocolate, melted
150g unsalted butter, melted
1 cup firmly packed brown sugar
1 cup hazelnut meal
4 eggs, separated
½ cup nutella hazelnut spread
Optional: 4 x Ferrero rocher chocolates, roughly chopped
1. Preheat oven to 180°C/160°C fan-forced. Grease deep 20cm-round cake pan; line base and side with baking paper.
2. Blend cocoa with the water in large bowl until smooth. Add chocolate, butter, sugar, hazelnut meal and egg yolks; stir until combined.
3. Beat egg whites in small bowl with electric mixer until soft peaks form; fold into chocolate mixture in two batches.
4. Pour mixture into pan; bake 50 minutes to 1 hour. Stand cake in pan 15 minutes before turning, top-side up, onto wire rack to cool.
5. Heat nutella in microwave for 10 seconds. Using a palette knife, spread over the top of the cake. Top with chopped Ferrero rochers