Mix butter and cream cheese together in large bowl, using a hand mixer or stand mixer.
Add sugar, egg yolks, vanilla and blend well.
Stir in flour, a cup at a time.
Roll on a floured counter top and roll out to about ⅓ to ½ inch thickness
Cut into circles, using cutters (or top of glass)
Bake on lightly greased cookie sheets at 350* for 8-10 minutes
For The Frosting
Mix melted butter and water together.
Whisk in powdered sugar until it is the consistency you want (I used about 1 ½ cup). The frosting should be more runny than thick. Almost the consistency of syrup.
Dip cooled cookies in frosting one at a time, set on rack to harden