Preheat Oven and Sift Flour - Preheat your oven to 325 degrees Fahrenheit. Sift the flour together with 3/4 cup of sugar.
Beat the Egg Whites - In a large bowl with an electric mixer, beat the egg whites and salt together until foamy. Then, add the cream of tartar and beat the mixture until soft peaks form.
Add the Sugar - Add the sugar in, 1/4 cup in at a time, beating after every addition. Beat the egg white mixture until stiff peaks form and gently fold in the vanilla extract with a rubber spatula.
Add the Flour - Carefully fold the flour into the egg white mixture, 1/4 cup at a time. After each addition, fold in by using an under and over motion. After the last of the flour is added, fold an additional 10 strokes.
Bake the Angel Food Cake - Carefully pour the batter into the pan. Bake for 55-60 minutes, until a toothpick inserted into the middle, comes out clean and the top is lightly browned.
Invert pan onto a wire rack on the counter and let it cool for two hours before removing. When ready to remove, run a knife around the edge to loosen it.
Make the Whipped Cream Topping - In a large bowl, use an electric mixer to beat the whipping cream, confectioners’ sugar, and vanilla. Beat the mixture at a high speed until stiff peaks form.
Decorate the Angel Food Cake - Cut your angel food cake in half horizontally. Fill the middle with a layer of whipped cream.
Add the remainder of the whipped cream to the top. Using an offset spatula, spread the whipped cream to create swirls. Arrange sliced strawberries, blueberries, and raspberries on top of the whipped cream. Arrange in a circular pattern or at random.