Frosting Thumbprints

1/2 cup butter
1/4 cup sugar
1 egg yolk, beaten
1 t. vanilla
1 cup flour
1/2 t. salt
1 egg white
1 cup chopped walnuts

Cream together butter and sugar. Beat in egg yolk and vanilla. Blend in flour and salt, sifted together. Shape into 1" balls. Dip in egg white; roll in nuts. Place on baking sheet lined with parchment paper. Dent each ball. Bake at 350 degrees for 5 minutes.

Remove from oven and dent again. Bake another 12 - 15 minutes. Cool. Fill with butter frosting.

Frosting:
2 cups confectioner's sugar
6 T. melted butter
1 T. cream
1/2 t. vanilla

Mix well. Tint with food coloring.