Whisk together dry ingredients in a medium bowl and set aside.
Cream together butter and sugar in a stand mixer, then add eggs one at a time, followed by vanilla extract and sour cream.
Add dry ingredients to the mixture and beat until just combined.
Chill the dough in the refrigerator overnight or at least two hours until firm.
Prepare baking sheets and preheat the oven to 425°F.
Roll out the cookie dough, cut out circles, and bake for 7 minutes.
Make the frosting by creaming butter and vanilla, then beating in powdered sugar, salt, and heavy cream until smooth and creamy.
Frost the cookies once cooled and add sprinkles.
Store the cookies in an airtight container with waxed paper layers or in a zip-close bag.
