Preheat the oven to 350°F (180°C) or 140°C for a fan oven. Line sheet trays with parchment paper and set aside.
In a medium bowl, stir together the flour, baking powder, baking soda, and salt; set aside.
In a separate large bowl, beat the butter and sugar together until light and fluffy. Add the eggs, sour cream, and vanilla extract and beat again, scraping down the sides of the bowl as needed.
Add the flour mixture in 2-3 smaller additions; mixing well after each addition.
Scoop the dough using a small cookie scoop (1.5 tablespoons) onto the prepared baking sheets 3” apart. Use damp fingers to smooth the tops and press down slightly.
Bake in the preheated oven for 7-9 minutes or until lighty golden and they spring back when gently touched.
Allow to cool completely before frosting.
For the frosting:
Beat the butter and powdered sugar until light and fluffy. Stir in the milk a little at a time until desired consistency is achieved.
Stir in the vanilla and salt. Add the food coloring if desired and mix well.
Frost each cooled cookie with a generous amount of frosting.
Notes
Use room temperature ingredients: It's key that you let the butter soften to room temperature, but did you know that you should also take the chill off of the eggs and sour cream? Set them on the counter for about an hour before you mix up the dough.
Try other flavors: Add a bit of almond extract or lemon zest to the dough to give these cookies a slightly different flavor. Use this recipe as your starting point!
For smoother cookies: Use slightly wet fingers to smooth out the dough balls before baking.
Go easy on the food coloring: You only need a tiny drop of gel food coloring to make pastel pink icing.
Let them cool: the cookies need to be completely cool before frosting them. Otherwise the icing will melt right off!
Be careful stacking these: The icing will dry a bit, but it won't completely harden like royal icing does. It's best to store sour cream cookies in a single layer.
Add sprinkles! Make these cookies even more festive by decorating them with rainbow sprinkles or specialty sprinkles that fit the theme for the day.