Preheat the oven to 325°F and line a 12-cup muffin tin with cupcake liners then set aside.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.

In a separate small bowl, whisk together the whole milk, sour cream, and vanilla extract.

Using a stand mixer or hand mixer, cream the butter and sugar together on medium speed until it is light and fluffy.

Scrape down the bowl and add the egg whites. Mix until incorporated.

Scrape down the bowl again.

To the creamed butter mixture, add half of the wet ingredients and then half of the dry ingredients and mix until incorporated.

Scrape down the bowl, and add in the second half of the wet and then dry mixture until fully incorporated.

Scoop batter into prepared cupcake liners filling ¾ of the way full. This is approximately ¼ cup of batter.

Bake the cupcakes for 20 to 22 minutes until the tops spring back when touched.

Remove from the oven and place on a cooling rack then allow to cool completely.

In a large bowl, add the butter and powdered sugar and beat together until the mixture is crumbly.

To the butter and sugar mixture, add the milk and vanilla extract and beat until smooth.

If needed, add additional milk to get the desired consistency.

Add a small drop of gel food coloring and mix thoroughly.

Place a piping bag into a large cup to hold upright, then scoop the prepared icing into the bag.

Gently squeeze the icing down to the end of the bag to remove air bubbles then twist the top to secure.

Trim the end of the bag off creating a medium-sized opening.

Starting at the outside, pipe the icing in a circle ending in the middle of the cupcake. Best results with using consistent light pressure as the icing flow out of the bag.