Preheat oven to 375 degrees. Grease cookie sheets or line with parchment paper.
Cream butter and sugar. Beat in egg, egg yolk, chocolate, milk, and vanilla. Sift together flour, baking soda, baking powder, and salt. Add to butter mixture; mix well. Fold in raisins and nuts.
Drop by teaspoons onto cookie sheet. Bake about 15 minutes. When cool, top with frosting.
Frosting: Cream all ingredients at medium speed until frosting reaches spreading consistency.
Makes 4 dozenRecipe submitted by Joyce on 11/30/00