Thumbprint Cookies
["1/2 c. soft butter", "1/2 tsp. vanilla", "1/4 c. brown sugar", "1 egg yolk"]
["Mix these together well.", "Stir in 1 cup flour and 1/4 teaspoon salt.", "Roll into 1-inch balls.", "Dip in slightly beaten egg whites, then roll in chopped nuts (1/2 cup).", "Place on greased cookie sheet about 1 inch apart.", "Bake 5 minutes.", "Press thumb in center, then bake about 8 minutes more in 375\u00b0 oven.", "Fill thumbprint with powdered sugar frosting.", "I make different color frosting."]
["butter", "vanilla", "brown sugar", "egg yolk"]