In a large bowl, combine the butter, sugar, vanilla and eggs until creamy.
In a separate bowl, combine the flour, cocoa, baking soda and salt. Slowly fold the dry mixture in with the wet we ingredients. Fold in peanut butter chips.
Drop by rounded tablespoons onto nonstick/greased cookie sheets and bake 9-11 minutes.
Notes
Do NOT overbake – they're even better when they are a little bit undercooked and fudgy. :)