Preheat the oven to 350°F. Lightly grease three 8 inch round cake pans and line with parchment, set aside. In the large bowl of a stand mixer with the paddle attachment fitted add the granulated sugar, flour, baking powder and salt. Turn the mixer to a low speed and mix to combine. 2 cups granulated sugar, 2¾ cups cake flour, 2½ teaspoons baking powder, ½ teaspoon salt
Add the butter and increase the mixer speed to medium. Beat for 3 minutes or until the texture of the ingredients looks like damp sand.
¾ cup unsalted butter
Turn the mixer to its lowest speed and gradually pour in the heavy cream, buttermilk and vanilla extract.
1 cup heavy cream, ½ cup buttermilk, 2 teaspoons vanilla extract
Turn the speed to medium and beat the ingredients together for 2 minutes. The cake batter will look very thick.
Stop the mixer and thoroughly scrape down the sides and bottom of the mixing bowl. Turn the mixer back on and mix on a medium speed for 30 seconds.
With the mixer on its lowest speed add the egg whites in thirds, beat for 20 seconds after each addition. At this stage the cake batter should look silky smooth. Do not over mix.
1 cup egg whites
Divide the cake batter between the three prepared pans. Bake in the preheated oven for 20-22 minutes or until the cakes are a very pale golden color, shrinking away slightly from the edges of the pan and feel springy when touched with your finger. A toothpick inserted into the middle should come out clean. Leave the cakes to cool in the pan for 10 minutes then invert onto a wire cooling rack to completely cool.