Stir together flour, soda and salt and set aside. In a mixing bowl, Beat butter for about 30 seconds, just to cream it a bit. Add sugars and peanut butter. Beat until fluffy. Add in egg and vanilla, beat well. Add flour mixture and mix until all combined.
fold in your chopped Butterfinger bars.
Shape dough into 1-inch balls then roll balls in granulated sugar
Place on ungreased cookie sheet and crisscross with a fork. You know what I'm talking about, the marks you make for peanut butter cookies. Don't place cookies too close together, these spread....alot.
Bake in a preheated 375 degree oven for 9-10 minutes, I cook mine for 9 1/2 minutes. Remove from oven and let rest for 2 minutes.