If you can’t find already ground almonds or hazelnuts, you can grind your own using a coffee grinder or high-powered blender.
The cake can be served with whipped cream or coffee ice cream, but frankly, it’s perfect as is.
- 7 ounces high-quality dark chocolate (at least 70 percent cacao), roughly chopped
- 6 large eggs, separated
- 1 cup powdered sugar, plus more for dusting
- 1/3 cup almond flour
- 1/3 cup hazelnut flour
- Butter or oil for greasing the pan
Preheat the oven to 325 degrees F. Generously grease a 9-inch round cake pan.
Melt the chocolate over a double boiler until smooth. Set aside.
In a large bowl, using an electric handheld mixer or by hand, whisk the egg yolks and sugar until pale in color and doubled in volume. Clean the whisk well, making sure that no grease remains, and in a separate bowl, whisk the egg whites to stiff peaks.
Using a spatula, mix together the egg and sugar mixture with the almond and hazelnut flour. Fold in the melted chocolate. Fold in the egg whites in two or three additions, and gently mix until the color is even and no streaks remain.
Pour into the greased pan and bake in the oven for 25 minutes, or until the edges begin to separate from the pan and the center is just jiggly. It will finish baking as it cools.
When cool enough to handle, invert the cake onto a decorative plate and dust with powdered sugar. Serve with whipped cream or fruit, or just by itself.