For the cakes – preheat the oven to 350, spray or butter 3, 8-inch round cake pans, line them with parchment and spray or butter the parchment.  In a medium bowl, whisk together the flour, cornstarch, salt and baking powder and set aside.  Using your electric mixer, cream together the butter and sugar for a few minutes until light and fluffy.  Add the egg whites one at a time, mixing well after each then add in the oil and extracts.

Run the mixer on low and slowly add the dry mix alternating with the milk in 2 or 3 batches and then mix until all is just combined, scraping down the sides if needed.  Using a sturdy spatula, gently fold in the sprinkles until they’re evenly distributed and then divide the batter among your 3 pans.  Smooth the tops and bake for about 25 minutes until the centers are all at 200 degrees.

Leave the cakes to rest in their pans for 10 minutes before turning them out onto a rack to cool completely.  I wrapped each and froze them because I was making them ahead but you can also make the frosting while the cakes are cooling.

For the frosting – using your electric mixer beat the butter for a couple of minutes until smooth and then gradually add and beat in the powdered sugar.  Add in the salt and extracts and then a tablespoon of milk at a time until you have the spreading consistency that you’d like.

Frost the cake as you wish and get some help decorating!