Chocolate Thumbprints II

Step 1
Preheat oven to 350 degrees F (175 degrees C). Grease cookie sheets.

Step 2
In a medium bowl, cream the butter and sugar together. Stir in 2 egg yolks, melted chocolate, and vanilla. Sift together the flour and salt; stir into the creamed mixture.

Step 3
In a small bowl, slightly beat the remaining egg whites. Roll dough into walnut sized balls. Dip balls into the egg whites, then roll in sugar (or chopped nuts if desired). Place the cookies onto the prepared cookie sheets and make a small indentation in the center with your thumb. Bake for 10 to 12 minutes in the preheated oven. When the cookies come out, press a chocolate kiss into the center of each one. Let stand, and then spread the chocolate candy like frosting, if desired.