In saucepan over medium low heat, melt chocolate (or cocoa) and butter. In medium bowl, beat eggs and sugar. Fold in flour just til mixed and then add vanilla and chocolate mixture.
Heat waffle iron and lightly coat with cooking spray. Drop batter by teaspoons full onto iron. Bake less than a minute and lift off with fork. Cool completely and dust with powdered sugar or frost with chocolate frosting.
To make frosting:
Combine chocolate (or cocoa), brown sugar, water and butter in saucepan. Bring to a boil and let cook for 3 minutes, stirring constantly. Remove from heat, add vanilla and cool completely. When mixture has cooled add 1 cup powdered sugar or enough to thicken frosting. Add nuts if using. Spread a small amount onto each cookie.