Sugar Cookie Bars

1 cup unsalted butter, softened
2 cups granulated sugar
4 large eggs - one at a time
2 t vanilla extract
Beat until light and fluffy, then add:
5 cups flour
1 t salt
1/2 t baking soda

Press into 12 x 14 baking sheet evenly.
Bake at 375 degrees for 15-20 minutes or until light golden brown.  Allow to cool completely before frosting.

Frosting:
1 cup unsalted butter, softened
1 t vanilla extract
pinch of salt
4 cups powdered sugar
5 T milk
food coloring, if desired
sprinkles
Store in airtight container overnight for softer cookies.