Sift cake flour, baking powder, and salt together in a large bowl. Set aside.
In stand mixer fitted with paddle attachment, beat egg whites on high speed until soft peaks form, about 2- 3 minutes. Set aside.
In your wiped out stand mixer bowl and still using paddle attachment, beat butter on high for 1 minute, or until smooth and creamy. Add the sugar and beat on high for 3-4 minutes. Scrape bowl as needed.
With mixer on low, add egg yolks and vanilla. Then beat on medium-high until combined.
With mixer on low speed, add in dry ingredients, scraping bowl as needed, in 3 additions alternating with milk. Mix until everything is just combined, do not overmix.
Remove bowl from stand mixer and using a rubber spatula, fold in egg whites.
Pour batter into prepared pans. Bake for 25-28 minutes or until an inserted toothpick comes out clean.
Remove cakes from oven and allow to cool completely in the pans on a wire rack.