Passover Chocolate Sponge Cake

Ingredients

 * 12 eggs, separated
 * 1½ cup sugar
 * 2 tbsp cold water
 * juice and grated rind of 1 orange
 * ½ lbs sweet chocolate, grated
 * ¾ cup matzo cake flour

Directions

 * 1) Preheat oven to 350 °F.
 * 2) Beat egg yolks and sugar until light and fluffy (about 7 minutes).
 * 3) Add cold water, orange juice, orange rind, chocolate and cake flour.
 * 4) Gently fold in stiffly beaten egg whites.
 * 5) Pour into a 10-inch tube pan with removable insert.
 * 6) Bake for 55 to 65 minutes or until cake springs back when gently pressed.
 * 7) Cool completely, inverted on cake rack, before removing from pan.