1/4 cup unsweetened cocoa powder
1/4 cup hot water
1 1/2 cups granulated sugar — divided
3/4 cup cake flour
1/4 teaspoon salt
12 egg whites
1 teaspoon cream of tartar
raspberries and nectarine slices — for garnish
1 Preheat oven to 350? F. In a medium bowl, combine cocoa and hot water. Mix well; cool. In a small bowl, combine 3/4 cup of sugar, flour, and salt. Mix well; set aside.
2 In a large mixing bowl, using an electric mixer set on high speed, beat egg whites until foamy. Add cream of tartar; continue beating until soft peaks form. Gradually add remaining sugar; beat until stiff peaks form.
3. Sift half of flour mixture over egg white mixture; fold gently until combined. Repeat with the remaining flour mixture. Stir 1 cup of egg white mixture into cocoa mixture. Gently but thoroughly fold cocoa mixture into remaining egg white mixture until combined.
4. Spoon the batter into an ungreased 10-inch tube pan. Run a small knife through batter to remove air pockets. Bake until springy to the touch and a toothpick inserted near center comes out clean, about 50 minutes.
5. Invert pan and place center tube over the neck of a bottle. Cool completely. Using a knife, loosen cake edges. Invert the cake onto a serving plate; garnish with raspberries and nectarine slices.