1. Prepare a cupcake pan with cupcake liners and preheat the oven to 350°F (176°C).
2. Combine the flour, baking powder and salt in a medium sized bowl and set aside.
3. Add the egg whites to a large mixer bowl and set aside. Set aside the egg yolks for later use.
4. Add the butter, sugar, oil and vanilla extract to a large mixer bowl and cream together until light in color and fluffy, about 3 minutes. Do not skimp on the creaming time. You should be able to see a visible change in the color and texture of the mixture when it’s ready.
5. Add the egg yolks one at a time, mixing until combined after each. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
6. Add about a third of the dry ingredients to the batter and mix until mostly combined.
7. Add half of the milk and mix until well combined. The batter might look a little curdled, but that’s ok.
8. Add another third of the dry ingredients and mix until well combined. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
9. Add the other half of the milk and mix until well combined.
10. Add the remaining dry ingredients and mix until well combined. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated. Do not over mix the batter. Set aside.
11. Grab the egg whites and whip on high speed with the whisk attachment until soft peaks form.
12. Gently fold about half of the whipped egg whites into the cake batter and gently fold together until mostly combined.
13. Add the remaining egg whites and sprinkles and gently fold together until well combined.
14. Fill the cupcake liners about 3/4 full and bake for 15-18 minutes or until a toothpick inserted into the center comes out clean.
15. Remove cupcakes from the oven and place on a cooling rack to cool.

To Make The Vanilla Buttercream And Decorate

16. To make the frosting, add the butter to a mixer bowl and beat until well combined.
17. Add about half of the powdered sugar and mix until well combined and smooth.
18. Add the vanilla extract and 1-2 tablespoons of water or cream and mix until well combined.
19. Add the remaining powdered sugar and mix until well combined and smooth.
20. Add additional water or cream as needed to get the right consistency frosting. Add salt to taste.
21. Pipe the buttercream onto the cupcakes. I used Ateco tip 847. Add sprinkles, if desired.