Step 1Heat the oven to 300 degrees. Spread the almonds into a shallow baking dish and toast, shaking the pan occasionally, until the almonds are light brown, about 15 minutes. Cool completely. Raise the heat to 350 degrees.
Step 2Butter and flour a 9-inch springform pan. Melt the chocolate in the top of a double boiler over simmering water. Cool slightly.
Step 3Grind the almonds with one-half cup sugar in a blender or food processor to make a fine meal. Combine with the cocoa powder, mixing well. Set aside.
Step 4Using an electric mixer, cream the butter until light. Beat in the remaining sugar, then add the salt and extract, scraping down the sides as needed.
Step 5Beat the egg yolks in one at a time. Using a rubber spatula or wooden spoon, stir in the melted chocolate, then the almond-cocoa mixture, mixing well.
Step 6In a clean bowl with clean beaters, beat the egg whites until soft peaks form. Stir about a third of the whites into the chocolate mixture, then gently but thoroughly fold in the remainder. Spread into the prepared pan. Gently bang the cake pan on the counter once to release air bubbles.
Step 7Bake 1 hour. Transfer to a rack and cool 20 minutes. Unmold onto a serving plate so the bottom faces up and cool completely.
Step 8Serve the cake plain or with a dusting of powdered sugar.