Preheat oven to 350 degrees Fahrenheit. Line cookie sheets with nonstick baking mats or spray with nonstick baking spray.
In the bowl of an electric mixer, cream together softened butter, brown sugar, white sugar, eggs, crunchy peanut butter and vanilla.
Add flour, baking soda, salt and Butterfinger pieces and mix until incorporated, scraping down the sides of the bowl in between.
Form or scoop dough into heaping, rounded 1 1/2" balls. Place at least 2" apart on cookie sheets. Press dough balls down to flatten slightly with the palms of your hands before baking.
Bake for approximately 9-10 minutes. Allow them to cool for about five minutes on the cookie sheets before removing them to a cooling rack to cool completely.