Preheat your oven to 350°F (175°C). Grease two 9-inch round cake pans with butter, line bottoms with parchment paper, and lightly flour sides. This preparation ensures cakes release easily after baking.

In a medium bowl, sift together all-purpose flour, baking powder, and salt. Sifting removes lumps and distributes leavening agents evenly, helping create a light, tender crumb in the finished cake.

In a large mixing bowl, beat softened butter and granulated sugar using an electric mixer. Continue mixing for three to four minutes until the mixture becomes pale, light, and fluffy.

Gradually add egg whites to the creamed butter mixture, beating well after each addition. Stir in vanilla extract. Egg whites maintain the cake’s bright color and create a soft, delicate texture.

Add dry ingredients to the butter mixture in three parts, alternating with milk. Begin and end with dry ingredients. Mix gently after each addition until just combined to avoid overmixing.

Evenly divide the batter between prepared cake pans and smooth tops with a spatula. Bake for 25 to 30 minutes until a toothpick inserted in the center comes out clean.

Remove cakes from the oven and allow them to cool in pans for about ten minutes. Transfer to a cooling rack and cool completely before frosting to prevent melting.

In a mixing bowl, beat softened butter until creamy. Gradually add powdered sugar, vanilla extract, salt, and heavy cream. Beat until frosting becomes smooth, fluffy, and easy to spread.

Place one cake layer on a serving plate and spread frosting evenly on top. Add the second layer and frost the top and sides, smoothing with an offset spatula for a clean finish.