First, let’s get friendly with the problem. Cake flour is basically all-purpose flour's delicate, delicate cousin.
It’s super finely milled and has a lower protein content (about 6-8%). Less protein means less gluten. Less gluten means a softer, tenderer crumb.
Think of it as the difference between a fluffy pillow and a leather shoe. You want the pillow for your cake. Got it? Good.