• Preheat the oven to 325°F and line a 12-cup muffin tin with cupcake liners then set aside. 
• Whisk together dry ingredients in a medium sized bowl (flour, baking powder, baking soda and salt).
• In a 2 cup liquid measurement cup, whisk together your whole milk, sour cream and vanilla.
• In a stand mixer with the paddle attachment, cream your butter, sugar, and vanilla on medium speed until the mixture is light and fluffy, scrape down the bowl. Add in your egg whites and mix until incorporated, scrape down the bowl 
• Add half of your wet and dry ingredients and mix until fully incorporated, scrape down the bowl, specifically looking for any unincorporated flour mixture. Add the second half of the wet and dry and mix on low until fully incorporated.
• Use a ¼ measuring cup or ice cream scooper to evenly portion out your cupcakes.  Bake your cupcakes for 20-22 minutes, until the tops spring back when touched. do not overbake or they will dry out!

The Buttercream:

• Add butter and powdered sugar to a bowl. Begin to beat together, the mixture will begin to turn crumbly.
• Start with 2 tablespoons of whole milk and vanilla. Mix until smooth. (add extra milk only if needed) 
• Add one small drop of gel food coloring and mix throughout.

To Decorate Cupcakes:

• Place icing in a piping bag squeezing the icing all the way down to the bottom of the bag. Cut a medium size whole at the bottom of the bag. Pipe the icing from the outside in. (start outside, work your way in) In a smooth motion. Or you can just use a knife and freestyle your icing!