Meanwhile, cream the wet ingredients: In a large mixing bowl, cream together small chunks of cold butter and the sugars on high speed until well combined, creamy, and fluffy (at least 4 minutes).
Combine the dry ingredients: Add cake flour, all-purpose flour, oats, cornstarch, baking soda, salt, and cinnamon to the creamy mixture, stirring until homogeneous. Fold in the raisins!