From SplendidTable.org; originally from At Home With Magnolia
This recipe makes a firm, decoratable cookie that would be perfectly lovely just plain, with a cup of tea. I like to use a snowflake-shaped cookie cutter, but any shape will do. White decorating sugar makes the cookie look extra special.

Cookies

2 ½ c all-purpose flour
1 tsp baking powder
¼ tsp salt
1 c (2 sticks) unsalted butter, softened
1 c sugar
2 large egg yolks, at room temperature
2 tsp vanilla extract

Icing

½ c + 2 T confectioners' sugar
¼ c heavy cream (or smaller amount of milk)
¼ tsp vanilla extract

Garnish

White decorating sugar

To make the cookies

To make the icing

To ice the cookies