Grab all of your needed ingredients and set aside. Preheat the oven to 350 degrees F.
In a large electric mixing bowl, combine butter and sugar and beat on medium speed until it starts to cream together and become smooth. Once smooth, add in the greek yogurt and combine well.
Next, add the egg and the vanilla extract and combine well.
In a small, separate bowl combine the flour, baking soda and cornstarch and give this a quick whisk with a fork to evenly distribute. Next, gradually add this to the wet mixture while on medium speed to thoroughly combine.
Finally, add in your Christmas Sprinkles of choice and give it one last good mix to distribute.
Time to bake! Roll the cookie dough out on to a floured surface to about 1.5" thickness. Using a cookie cutter or the rim of a glass cup, cut out cookies the size of your choice. I typically like these cookies to be large, usually 4-6" across.
Bake these cookies on a parchment lined baking sheet for 12-14 minutes for larger cookies. Adjust the time accordingly if doing something smaller.
While the cookies are baking, combine all of the ingredients for the buttercream in your mixer with the whisk attachment. Start with 4 tbsp of milk and gradually add more as needed, the moisture content in every stick of butter is different which can make vast variations in your icing, hence the range. Once whipped and smooth, add in your Christmas sprinkles and set aside.
Once the cookies have all cooked and cooled completely, it is time to ice! I like to use an icing piping bag for the best results, but decorate which ever way feels right to you.
