Preheat oven to 350 degrees. Coat a 9x13 baking dish with cooking spray.
In the bowl of a stand mixer fitted with the paddle attachment or a large mixing bowl with an electric mixer, beat butter until pale and fluffy. Add sugar, continue to beat.
Add eggs, one at a time.
Sift together flour, baking soda and salt. Gradually add to wet ingredients. Do not overmix.
Fold in butterscotch chips by hand.
Spread into prepared baking dish.
Bake 30 to 35 minutes or until it passes the toothpick test.
Remove and allow to cool completely before cutting into 16 bars.
If you've tried this recipe, come back and let me know how it was!