PreparationMake cake: Preheat oven to 350°. Butter mold and dust with sugar, knocking out excess. Stir together ground almonds, chocolate, and spices in a bowl. Beat yolks with 1/4 cup sugar in another bowl with an electric mixer until thick and pale, then beat in zest. Beat whites with salt with cleaned beaters in a large bowl until they just hold soft peaks. Gradually beat in remaining 1/4 cup sugar and beat until whites just hold stiff peaks. Stir one third of whites into yolk mixture to lighten, then fold in remaining whites in 2 more batches. Fold in ground almond mixture. Pour batter into mold and bake in middle of oven until golden and a tester comes out clean, about 45 minutes. Cool cake in mold on a rack 10 minutes, then invert onto rack and cool completely. Make icing: Melt chocolate with 1 tablespoon butter in a small heavy saucepan over very low heat, stirring. Remove from heat and add remaining 5 tablespoons butter, 1 tablespoon at a time, stirring until smooth. Transfer icing to a bowl and chill, covered, until slightly thickened and spreadable, about 30 minutes. Decorate cake: Spread icing over cake with a small metal spatula. Stick points of almonds into cake in straight rows, following ridges, to resemble a porcupine. Chill cake until icing is set, at least 1 hour. Transfer cake to a platter and bring to room temperature before serving. Cooks' note:• You can chill iced cake, loosely covered, up to 3 days.
PreparationMake cake: Preheat oven to 350°. Butter mold and dust with sugar, knocking out excess. Stir together ground almonds, chocolate, and spices in a bowl. Beat yolks with 1/4 cup sugar in another bowl with an electric mixer until thick and pale, then beat in zest. Beat whites with salt with cleaned beaters in a large bowl until they just hold soft peaks. Gradually beat in remaining 1/4 cup sugar and beat until whites just hold stiff peaks. Stir one third of whites into yolk mixture to lighten, then fold in remaining whites in 2 more batches. Fold in ground almond mixture. Pour batter into mold and bake in middle of oven until golden and a tester comes out clean, about 45 minutes. Cool cake in mold on a rack 10 minutes, then invert onto rack and cool completely. Make icing: Melt chocolate with 1 tablespoon butter in a small heavy saucepan over very low heat, stirring. Remove from heat and add remaining 5 tablespoons butter, 1 tablespoon at a time, stirring until smooth. Transfer icing to a bowl and chill, covered, until slightly thickened and spreadable, about 30 minutes. Decorate cake: Spread icing over cake with a small metal spatula. Stick points of almonds into cake in straight rows, following ridges, to resemble a porcupine. Chill cake until icing is set, at least 1 hour. Transfer cake to a platter and bring to room temperature before serving. Cooks' note:• You can chill iced cake, loosely covered, up to 3 days.