I have so often used potato starch as a thickener for sauces, soups, and stews but for adding it to my flour for baking, this is my first.
Potato starch is not potato flour. Potato flour is dehydrated potatoes ground into powder and is much heavier and denser. Potato starch is the result of an extraction process removing the starch only from the potato. Think of the white foam that floats to the top when you boil potatoes, that's potato starch. Potato starch has no gluten. It is used in recipes for those who are gluten intolerant.
The Yellow Butter Cake Recipe is HERE