cutout sugar cookies

these are absolutely the best sugar cookies i've ever tasted. the recipe comes from my husband's cousin, alicia.

1 cup butter, room temp.
1/2 cup sugar
2 large egg yolks
1 tsp vanilla
2 1/2 cups flour

preheat oven to 300'.
beat together the butter and sugar, then add in the egg yolks and vanilla.
add the flour and beat until combined.
divide in half and roll out to 1/4" thick.
cut out and bake 15 minutes. ice when cooled.

icing:
3 cups powdered sugar
1 tsp vanilla
1/4 cup water (maybe less)

decorate!

i don't understand why these are so good when there isn't much sugar, no salt, and no leavening. but they are fantastic.