You can lso just grind almonds in a food processor and then add some flour from the recipe to grind up finer. That is in essence what almond flour is, finely ground almonds. I do this any time I don't have almond flour on hand.
She is absolutely right. Just make sure 1- the almonds are peeled (little brown speck in your cake are not pretty) and 2- don't overprocess, or you will wind up with almond butter...but that's another show ....