Amazingly Buttery Thumbprint Cookies

Directions

Cream butter; gradually add sugar, beating at medium speed of an electric mixer until light and fluffy.

Add egg yolks, one at a time, beating well after each addition. Stir in vanilla. Combine flour and salt; add to creamed mixture, mixing well.

Chill dough at least 1 hour. Shape dough into 1 inch balls, place about 2 inches apart on ungreased cookie sheets. Press thumb in each cookie leaving an indention.

Bake at 300℉ (150℃) for 20 to 25 minutes; do not brown. Cool on wire racks. Spoon about ½ teaspoon frosting or glaze in each cookie indentation.