Preheat oven to 375 degrees F. In a large bowl, beat butter with an electric mixer on medium to high speed for 30 seconds. Add granulated sugar, brown sugar, baking powder, baking soda, and salt. Beat until combined, scraping side of bowl occasionally. Add eggs and vanilla; beat until combined. Beat in as much of the flour as you can with the mixer. Using a wooden spoon, stir in any remaining flour. Stir in cashews and butterscotch pieces.