Preheat oven to 350 degrees and grease a 9x11 baking dish with baking spray.
Cream butter and peanut butter together until light and fluffy, about 1-2 minutes.
Add in brown sugar and white sugar, and mix until well combined. Add in eggs, 1 at a time, beating well after each addition. Add in vanilla extract.
In a separate bowl, mix all dry ingredients together. Slowly incorporate the dry ingredients into the wet ingredients. Once combined, add in butterscotch chips.
Spread dough evenly in the baking dish and bake for 20-25 minutes, or until the top is just beginning to turn golden brown.
Enjoy!