
Preheat the oven to 350 degrees F. Lightly grease a 9X13-inch pan or line with foil and lightly grease the foil (for easier cleanup). I use a metal pan; if using glass, you may want to decrease the oven temp to 325 degrees.
In the bowl of a stand mixer fitted with the paddle attachment or in a large bowl using a handheld electric mixer, beat the butter, peanut butter, brown sugar, granulated sugar, baking soda and salt together until light and fluffy, 1-2 minutes, scraping down the sides of the bowl as needed.
Add the eggs and vanilla and beat until well-combined. Add the quick oats, old-fashioned oats, chocolate chips and butterscotch chips and mix until evenly combined.
Spread the dough evenly in the bottom of the prepared pan. Bake for 20-25 minutes until the edges are lightly golden - don't overbake or the bars might be dry and crumbly. Cool the bars in the pan before cutting into squares. These bars freeze great!