In a large bowl (I used my KitchenAid mixer), cream together the butter, peanut butter, white sugar, and brown sugar until smooth. Beat in the eggs one at a time, then stir in the vanilla.
Combine the flour, cocoa, and baking soda; stir into the peanut butter mixture. Mix in the chocolate chips, peanut butter chips, and Reese’s Pieces.
Drop by tablespoonfuls onto ungreased cookie sheets. Push one (or if you are over-the-top, like me, two) peanut butter cup half into the center of each ball of dough. Bake for 8 to 10 minutes. ***Let cool for 1 or 2 minutes on sheet before removing, or they will fall apart.***
Notes
Note from Anna: Recipe calls for regular butter and does not include salt. If you use unsalted butter, you might want to add some salt (generous half teaspoon) to the batter to keep the cookies from tasting flat.