Just because you can't have gluten, it doesn't mean you can't have dessert. Instead of white flour, this recipe used Cup4Cup gluten-free flour, which you can find in our American Made marketplace on amazon.com.
Preheat oven to 350 degrees. With a fine sieve, sift together flour, cornstarch and 3/4 cup sugar four times into a small bowl. Set aside.
In the bowl of a standing mixer, whisk together egg whites and warm water on medium speed until foamy. Add salt, cream of tartar, and vanilla; beat until soft peaks form, about 3 minutes. Increase speed to medium-high and sprinkle in remaining 1/2 cup sugar, 1 tablespoon at a time. Beat until stiff but not dry.
In six additions, sift dry ingredients over meringue, folding in quickly but gently. Pour batter into an ungreased 10-inch tube pan with removable bottom. Run a knife through the batter to release air bubbles. Smooth top with an offset spatula. Bake until golden brown and springy to the touch, 40 to 45 minutes. Invert pan on its legs and let cool completely, about 1 1/2 hours. Carefully run a long offset spatula or knife around the inner and outer perimeter of the pan to loosen. Arrange cake on a plate bottom-side up. Use a serrated knife to slice cake. Serve with berries and whipped cream. Store cake at room temperature up to 2 days in an airtight container or wrapped in plastic.