Topping:

1/2 cup packed brown sugar

1/4 cup sour cream

1/2 teaspoon cinnamon

1 cup chopped walnuts

Dough:

1/2 cup butter

1 cup packed brown sugar

1 egg

1 teaspoon vanilla extract

2 cups flour

1/2 teaspoon baking soda

1/4 teaspoon salt

Icing:

1/2 cup powdered sugar

1 tablespoon water

Topping: Combine sugar, sour cream, and cinnamon together in a small mixing bowl; stir until smooth. Stir in walnuts; set aside.

Dough: Cream butter and sugar with an electric mixer in a medium mixing bowl. Add egg and vanilla; beat until light and fluffy. On low speed, gradually add the dry ingredients, beating until just smooth. Roll in to 1″ to 1 1/2″ balls, place on ungreased cookie sheet. (Cookie will spread while baking, so leave room between cookies.) Make a wide round depression in the center of each cookie with your fingertip, leave a rim. Fill the depression with topping, mounding fairly high above the rims. Bake at 350 degrees for 15 to 20 minutes or until filling is set. Transfer to rack to cool.

Icing: Mix the powdered sugar and water with a wire whisk until smooth. Drizzle over cookies.