Step 1

Move oven rack to the lowest position.  Preheat oven to 350°F.

Step 2

In a large mixing bowl, separate egg whites and let them stand at room temperature for 30 minutes.

Step 3

Sift powdered sugar and flour together 3 times.  Set aside. DON'T SKIP THIS STEP.

Step 4

Add cream of tartar and vanilla to room temperature egg whites.  Using a hand mixer, beat on medium speed until soft peaks form.  Add in granulated sugar, 2 tablespoons at a time, until stiff peaks form.

Step 5

Sift about one-fourth of the flour sugar mixture into the beaten egg whites and gently fold in.  Repeat until all the flour sugar mixture is incorporated.  Pour into an ungreased 16 cup tube pan.

Step 6

Gently cut through the batter to remove any large air pockets.

Step 7

Bake for 40-45 minutes or until the top springs back when lightly touched.

Step 8

Immediately invert cake in the pan.  Cool completely.  Loosen side of the cake from the pan.  Remove the cake.

Step 9

Serve with fresh berries and whipped cream if desired.