Here in the UK, almond flour isn't a commonly bought product sold on the shelves of mainstream supermarkets. It's generally found in health stores and can be fairly pricey to purchase. I know that in the States it is more commonly found and hence used in recipes. Personally, I have never baked with it but from what I read, yes you can use almond flour in the cupcakes. That being said, ground almonds have a very specific graininess and texture that you notice in the baked sponge. You definitely won't achieve this when using almond flour. Personally, I have never baked with almond flour, but if you do a straight swap, then let me know how you go!