1/2 c. butter, softened
1 c. packed brown sugar
1 egg
1 tsp. vanilla extract
1 3/4 c. all-purpose flour
1/2 tsp. baking soda
1/4 tsp. salt

Filling:

1 c. chopped walnuts
1/2 c. packed brown sugar
1/4 c. sour cream

In a bowl, cream butter and brown sugar. Beat in egg and vanilla. Combine flour, baking soda and salt. Gradually add to the creamed mixture. Refrigerate for 30 minutes. Roll into 1-inch balls. Place 2-inches 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°F for 11 to 13 minutes or until lightly browned. Cool for 5 minutes before removing to wire rack.