1/2 c. butter
1 egg, separated
1 c. all purpose flour
Finely chopped nuts
M&M peanut chocolate candies
1/4 c. firmly packed brown sugar
1/2 tsp. vanilla
1/4 tsp. salt
1 can vanilla creamy frosting

Blend butter and sugar in a bowl; stir in egg yolk and vanilla. Sift flour and salt into a bowl; mix well. Chill for 1 hour. Roll into 1" balls. Dip into slightly beaten egg whites. Roll in nuts. Place 1" apart on cookie sheet. Bake in moderate oven at 350 degrees for 5 minutes. Press thumb gently in center of each; bake for 5 minutes longer. Cool. Fill with frosting. Garnish with M&M peanut chocolate candies.