1 1/2 cups white sugar divided
12 egg whites
1 1/2 teaspoons vanilla extract
1 1/2 teaspoons cream of tartar
1/2 teaspoon salt
Preheat the oven to 375 degrees F. In a bowl, sift together the flour, and 3/4 cup of the sugar, set aside. In a large bowl, whip the egg whites, until soft peaks form. Add the vanilla, cream of tartar and salt, and continue whipping until medium stiff peaks form. Gradually add the remaining sugar, while continuing to whip whites to stiff peaks. After stiff peaks form, fold in the sifted ingredients gradually, one third at a time. Do not overmix. Put the batter into at 10" tube pan. Bake for 40 to 45 minutes in the preheated oven, until the cake springs back when lightly touched. Flip the tube pan upside down and allow to cool completely. When cool, run a knife around the edge of the pan and invert onto a plate. To assemble cake, cut into thirds. Divide Orange Whipped Cream between layers, filling center hole and smoothing excess around cake. Frost with Orange Buttercream.