Walnut Thumbprint Cookies

1/2 cup butter, softened
1 cup packed brown sugar
1 egg
1 teaspoon Spice Islands® pure vanilla extract
1-3/4 cups all-purpose flour
1/2 teaspoon baking soda
1/4 teaspoon salt

FILLING:
1 cup chopped walnuts
1/2 cup packed brown sugar
1/4 cup sour cream

In a large bowl, cream the butter and brown sugar until light and
fluffy. Beat in egg and vanilla. Combine the flour, baking soda and
salt; gradually add to the creamed mixture and mix well. Refrigerate
for 30 minutes.
Roll into 1-in. balls. Place 2 in. apart on greased baking sheets.
Using the end of a wooden spoon handle, make an indentation in the
center of each ball.
Combine filling ingredients; spoon about 1 teaspoonful into each
cookie. Bake at 350° for 11-13 minutes or until lightly browned. Cool
for 5 minutes before removing to wire racks. Yield: about 3 dozen.