For the cookies
·         1/2 cup sour cream
·         1 cup sugar
·         1/2 cup butter, softened
·         2 eggs
·         1/2 teaspoon vanilla extract
·         3 cups all-purpose flour
·         1 and 1/2 teaspoon baking powder
·         1/2 teaspoon baking soda
·         1/2 teaspoon salt

For the Frosting
·         4 cups powdered sugar
·         2 teaspoons vanilla extract
·         2 tablespoons heavy whipping cream
·         1/2 cup butter, softened
·         1/2 cup vegetable shortening
·         Sprinkles (optional)

For the cookies
1.      Preheat oven to 350 degrees Fahrenheit
2.      In a large bowl combine sour cream, sugar, butter, eggs and vanilla and mix well.
3.      In a smaller bowl combine flour, baking powder, baking soda and salt
4.      Add dry ingredients to wet mixture and mix until everything is just incorporated.
5.      Scoop out even size scoops of dough and then roll in a ball
6.      Place on a cookie sheet and slightly flatten with your hand so it's in a circular shape.
7.      Place cookie sheet in oven and bake for 8 minutes
8.      Transfer cookies to a cooling rack and let cool completely before frosting.

For the frosting
1.      Cream together butter and shortening with mixer on medium speed for about 2 minutes.
2.      Add 1/2 cup powdered sugar and beat until smooth.
3.      Add another 1/2 cup and beat until smooth.
4.      Add vanilla and beat until smooth.
5.      Add the remaining sugar and milk, making sure you end with sugar. 
6.      Continue to mix on medium until smooth.