Cook Time: 45 minutes
Prep Time: 20 minutes
1 & 1/2 cups (360 ml) egg whites (you will need about 12 large egg whites)
1 & 1/2 cups (300 grams) granulated white sugar, divided
1 cup (100 grams) sifted cake flour
1/4 cup (25 grams) unsweetened cocoa powder (regular or Dutch-processed), sifted
1/4 tsp salt
1 tsp cream of tartar
2 tsp pure vanilla extract
Note: Cream of Tartar is tartaric acid and is a fine white crystalline acid salt which is a by-product of the wine-making industry. It is used when whipping egg whites to stabilize them and to prevent over beating and the whites drying out.
1. Preheat oven to 350 degrees F (180 degrees C) and place rack in center of oven. Have ready an ungreased 10 inch (25 cm) two piece tube pan.
2. Separate the eggs, whites in one bowl and yolks in another. Cover whites (you need 1 1/2 cups (360 ml)) with plastic wrap and bring to room temperature (about 30 minutes). Cover yolks and store in refrigerator or freezer for another use.
3. In another bowl, whisk or sift together 3/4 cup (150 grams) granulated white sugar, the sifted cake flour, sifted cocoa powder, and the salt.
4. In your electric mixer, with the whisk attachment, (or with a hand mixer) beat the egg whites until foamy. Add the cream of tartar and continue to beat until soft peaks form. Gradually beat in the remaining 3/4 cup (150 grams) granulated white sugar, a tablespoon at a time, until stiff and glossy peaks form. Beat in the vanilla extract.
5. Sift the flour mixture (about one quarter of the flour mixture at a time) over the egg whites, and gently fold the flour into the egg whites using a rubber spatula or wire whisk. (It is important not to over fold the batter or it will deflate.)
6. Pour the batter into the pan and run a metal spatula or knife through the batter to get rid of any air pockets. Smooth the top and bake in the oven for about 35 - 45 minutes or until a wooden skewer inserted in the center of the cake comes out clean and the cake springs back when gently pressed. Do not over bake. (The top of the cake will have cracks.)
7. Immediately upon removing from the oven invert (turn upside down) the pan. Suspend the pan by placing the inner tube on the top of a wine bottle or flat topped glass. Allow the cake to cool completely (about 1 1/2 hours). Then run a metal spatula or knife around the sides and center core of the pan to loosen the cake and then remove the cake from the pan. Next, run a metal spatula or knife along the bottom of the pan and remove. Place onto a serving plate. The cake will keep covered for a few days at room temperature or for about a week in the refrigerator.
8. This cake can be eaten alone with just a dusting of cocoa powder or confectioners' sugar. Can be served with fresh berries and softly whipped cream.