Cream sugar and butter in mixer till creamy. Add eggs and vanilla, beat till well-mixed.
Blend in flour, baking powder, and salt. Continue beating until well mixed. Beat in melted chocolate on low speed just until mixed.
Shape into slightly flattened balls (rounded teaspoonfuls). Bake on ungreased cookie sheets at 375 degrees F (190 degrees C) for 7-8 minutes or until set. Cool for about a minute, then remove to wire racks to cool.