When baking a cake, the most common and familiar method of aerating the batter is creaming the butter and sugar together. When you beat butter and sugar, they create small air pockets that expand and make your cakes rise when baked. The trouble in this method is that once you incorporate the rest of your dry and wet ingredients, you run the risk of over-mixing the cake batter that could yield a tough, heavy, and chewy cake.
A different technique has been picking up popularity recently because of the soft and tender cakes that it yields. Here, dry ingredients are mixed with the solid fat component (usually butter) of the cake batter, and then wet ingredients are added in batches until everything is combined. The secret is really mixing butter + flour first (or other dry ingredients).
This method, explained by the legendary cookbook author Rose Levy Beranbaum, will reduce the gluten formation in the flour by first coating the flour in fat before the liquids are incorporated. In other words, the cake will bake into a tender, well-risen treat.
Mix things up in the kitchen the next time your make your favorite vanilla cake recipe. All you have to do is change the order of combining your cake ingredients: in a large bowl, mix flour, leavening agents, and sugar together. Mix in the butter and beat on low-medium speed until grainy. In a separate bowl, mix your eggs, vanilla, and milk together. Add in 3 batches, beating for 15 seconds on medium speed after every addition. Beating in the eggs will add structure to your cake.