Position a rack in the lower third of the oven and preheat to 350 degrees. Grease the sides of the springform pan and line the bottom with parchment paper.
Combine the almonds, chocolate, 1/2 cup of the sugar, and the salt in a food processor and pulse until the almonds and chocolate are very finely chopped but not completely pulverized. Set aside.
Use a mixer and large bowl to beat the egg whites with cream of tartar until soft, moist peaks are formed. Gradually add the remaining 1/2 cup sugar and continue to beat until egg whites are stiff but not dry. Add one third of the nut mixture to the egg whites and fold in with a large rubber spatula until nearly incorporated. Fold in half of the remaining nuts, then fold in the rest of the nuts.
Scrape the batter into the prepared pan and spread it evenly. Bake until the torte has risen and is golden brown on top and a toothpick inserted in the center of the cake comes out clean, or with just a little melted chocolate, approx 25-30 minutes.
Set the pan on a rack to cool for 10 minutes. Remove the sides of the pan and invert the cake onto the rack. Remove the bottom of the pan and then the parchment liner. Turn the cake right side up and cool completely. Cover or wrap tightly, and store for up to 3 days at room temperature.
To serve, transfer cake to a serving plate. Dust with powdered sugar or cocoa powder and serve slices with a dollop of whipped cream, if desired.