Preheat the oven to 350 degrees F. Generously coat a 9-inch x 13-inch baking pan with non-stick cooking spray, or line the pan with parchment paper. Set aside.
In a large mixing bowl, beat together the butter and sugar for 1 minute on medium speed until fluffy. Add the vanilla and eggs and mix to combine.
In a medium mixing bowl, stir together the flour, baking powder, and salt. Add the dry ingredients to the wet ingredients and mix until just combined.
Use a rubber spatula or wooden spoon to fold in the butterscotch baking chips by hand until well distributed. Spread the cookie dough in an even layer in the prepared baking pan.
Bake for 30-35 minutes or until the bars are set in the middle.
Remove from the oven and place the pan on a wire rack. Cut into 15 bars while still warm. Allow to cool completely.