Preheat oven to 350 degrees. Line a large baking sheet with parchment paper.
Combine butter and both sugars in a mixing bowl. Use an electric mixer to beat until blended.
Add eggs and beat until mixed in well.
Mix in vanilla, flour, baking soda, salt, and peanut butter just until blended.
Chop butterfingers into coarse chunks and mix in.
Drop dough by rounded tablespoonfuls onto prepared sheet spacing them apart enough so they have plenty of room to spread. Bake for 14 to 16 minutes, just until edges start to turn golden.
Notes
If just using one baking sheet, you will have to bake multiple batches. Keep batter in refrigerator until ready to bake.