Grease and line with parchment paper a 8 or 9 inch (20-23 cm) springform pan (with a removable base). Preheat oven to 180°C (350°F).
Place the peeled almonds into a food processor and process until finely ground but with still some remaining chunky pieces for a crunch texture.
Melt chocolate and butter over a bain-marie until smooth. Let it cool slightly.
Meanwhile separate egg whites from yolks.
Mix yolks with ½ cup (100g) sugar and salt until thick and pale yellow colored.
Mix in cooled chocolate and add ground almonds.
Whip egg whites until foamy using a mixer. Gradually add ¼ cup (50g) sugar and whip until stiff peaks form. Gently fold the whipped whites into chocolate mixture.
Pour batter into prepared pan and bake for 30-40 minutes until a toothpick inserted into the center comes out with few crumbs attached.
Let it cool completely in the pan over a cooling rack.
When cooled invert onto a serving platter and dust with powdered sugar.
Serve if desired with whipped cream and fresh berries.