Best Ever Butter Cookies

This recipe came from my mother in law and they are really the best ever.

1 cup butter (2 sticks)
1 cup sugar
2 egg yolks
2 cups of flour
2 teaspoons vanilla
1/2 teaspoon salt

Cream butter and sugar with electric mixer. Add eggs and mix well.  Add remaining ingredients and mix until combined.

Break off small pieces and roll into one inch balls  Place on greased cookie sheet and make a small indentation in the center of each one.  Fill with your favorite jam or jelly.  We like apicot, cherry or raspberry.  Bake at 350 degrees for 15 - 20 minutes.