Chewy butterscotch peanut butter cookie bars have no flour! Hearty, chewy, soft baked, and loaded with chocolate and butterscotch chips. This cookie bar recipe makes lots of cookie bars so it's perfect for snacks (freeze extras) or big gatherings.
Heat oven to 350 degrees. Prepare a cookie sheet (about 12" x 18") and spray with cooking spray.
In a large bowl with a hand mixer, or in the bowl of a stand mixer with the paddle attachment, combine the butter, peanut butter, sugar, and brown sugar. Beat together for 1-2 minutes until it's pale in color and fluffy looking.
Add in the vanilla extract and eggs. Beat together until combined.
Add the quick oats, old-fashioned oats, and baking soda. Mix on low speed until combined. Add chocolate chips and butterscotch chips (reserve some for top of bars if wanted) and mix together just until combined.
Dump the cookie dough onto the prepared cookie sheet and spread out evenly. It will be sticky so use the back of a silver table spoon, or the butter wrapper, or spray your hands lightly with cooking spray.
Sprinkle the reserved chocolate chips and butterscotch chips on top and gently press them into the bars.
Cook for 17-20 minutes. I have never cooked these bars for longer than 17 minutes. Because of the no flour, they will appear underdone and slightly gooey but that's normal. Take them out of the oven and place the cookie sheet on a cooling rack. Let the bars cool for 30-45 minutes. They will come together and finish cooking slightly while cooling.
Use a pizza wheel cutter to cut these bars easily. Leftovers can be stored at room temperature covered. Or, place the bars in sandwich size Ziploc bags and store in the freezer. Eat cold, let sit at room temperature, or microwave for 10 seconds or so.
Natural peanut butter is thicker and does not do well in baked goods like cookie bars. Maybe this personal preference, so try at your own risk, but natural peanut butter is drier and does not have the added oil/moisture to it.
After lots of recipe testing, I have found the combination of both quick oats and old-fashioned oats gives the best chewy texture. But, others have told me they've made this recipe with all quick oats or all old-fashioned oats. So it's something you can try if you only have one kind. But I do recommend using both kinds of oats.