1. Preheat oven to 350˚F (180ºC). Grease 8-inch (2 L) springform pan.
2. Combine chocolate and butter on top of double-boiler over barely simmering water. Stir until melted and combined. Remove from heat; cool slightly.
3. In medium bowl, use electric mixer to beat egg whites until glossy and soft peaks form. Set aside.
4. In separate bowl, beat egg yolks and sugar until thick, creamy and light in colour.
5. Using rubber spatula, stir chocolate mixture into egg yolk mixture.
6. Add hazelnut meal to chocolate mixture, gently folding until the hazelnut meal is completely combined.
7. Stir egg whites into chocolate mixture one-third at a time, gently folding until no more streaks of white show.
8. Scrape batter into prepared pan. Bake for 45 minutes or until skewer inserted into middle of cake comes out mostly clean with some crumbs clinging.
9. Cool in pan for 10 minutes. Remove side from pan and cool cake completely on cake rack. Serve with whipped cream.
10. Tip: This cake keeps well overnight, at room temperature, covered with plastic wrap or foil.