Soft Sour Cream Sugar Cookies

I made these delicious cookies for our 4th of  July cookout. The next day the leftovers were sitting on the counter and my 2 year old came walking into the den with one like it was no big deal that she had snatched a cookie without asking, I asked her "what are you doing?" and she said "oh just eating sprinkles!", she is a mess! This recipe is I Heart Eating.

Cookies:
2 1/4 cup flour
2 tsp baking powder
1/2 tsp salt
3/4 cup butter (room temperature)
1/2 cup sugar
1/2 packed brown sugar
2 large egg yolks
1 1/2 tsp vanilla extract
1/2 cup sour cream
2 tbsp milk

Frosting
1/2 cup butter (room temperature)
3 cups powdered sugar
2-4 milk
1/2 tsp vanilla extract
sprinkles

Heat oven to 350. In a mixing bowl whisk together flour, baking powder and salt. In a separate bowl beat together butter, white sugar and brown sugar. Beat in the egg yolks one at a time, scarping down as needed. Mix in vanilla extract, sour cream and milk. Stir in the dry ingredients until just combined. Line a baking sheet with parchment paper. Place 1 1/2 tbsp scoops onto the cookie sheet. Bake for 10-13 minutes. Remove from oven and let cool for 10 minutes before moving to a wire rack to finish cooling.  Once the cookies are cool make the frosting. Beat together the butter, powdered sugar, milk and vanilla extract. Spread the frosting on the cookies and top with sprinkles