1/2 c. butter
2/3 c. sugar
1 egg yolk
2 tbsp. milk
1 tsp. vanilla
1 c. unsifted flour
1/3 c. Hershey's cocoa
1/4 tsp. salt
1/2 c. chopped pecans (optional)
Vanilla filling (below)
Granulated sugar

Cream butter, sugar, egg yolk, milk and vanilla. Combine flour, cocoa, and salt; blend into creamed mixture. Stir in finely chopped pecans. Chill dough about an hour or until firm enough to handle.

Prepare vanilla filling. Roll dough into 1-inch balls. Roll in sugar. Place on lightly greased cookie sheet. Press thumb gently into center of each cookie. Bake at 350 degrees for 10 to 12 minutes, or until set.

As soon as removed from oven, spoon small amount of filling into thumbprint. Cool slightly before removing from cookie sheet. Cool completely before storing.

VANILLA FILLING:

Thoroughly combine 1 cup confectioners' sugar, 2 tablespoons butter, 4 teaspoons milk and 1/2 teaspoon vanilla. Use about 1/2 teaspoon for each cookie.