I thought cake flour was a scam until I ran my own test
For a long time I figured all purpose flour was fine for everything and cake flour was just a way for companies to sell me a second bag. Then I read Rose Levy Beranbaum's baking book and saw her note that cake flour has about 7 to 8 percent protein compared to 10 to 12 in all purpose, which is why it makes such a soft crumb. I baked two yellow cakes side by side, same recipe, one with each flour, and the cake flour one rose higher and felt like a cloud. Now I keep a bag in the freezer. Does anyone else buy cake flour for everyday baking or just save it for special stuff?