These ultrachocolate cookies are, hands down, some of the best ever to come through our test kitchen.
Beat butter and shortening at medium speed with an electric mixer until creamy; gradually add sugars, beating until light and fluffy. Add eggs and vanilla, beating until blended.
Combine flour and next 3 ingredients; gradually add to butter mixture, beating until blended. Stir in cookies, candy bars, and desired amount of chocolate morsels. Chill dough 30 minutes.
Drop dough by 1/4 cupfuls 2" apart onto baking sheets lined with parchment paper. Bake at 350° for 10 to 12 minutes or until barely set. Cool on baking sheets 10 minutes. Transfer to wire racks to cool completely.