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Slab of monster cookie bars cut into squares on wood board.

Butterscotch PB Monster Cookie Bars

Yield: 24 Servings (9X13-inch pan of bars)
Prep Time: 20 minutes
Cook Time: 25 minutes
Total Time: 45 minutes

Ingredients

  • ½ cup (113 g) salted butter, softened to room temperature
  • 1 cup (255 g) creamy peanut butter
  • ⅔ cup (141 g) light brown sugar
  • ⅔ cup (141 g) granulated sugar
  • 1 teaspoon baking soda
  • ¼ teaspoon salt
  • 2 large eggs
  • 1 teaspoon vanilla extract
  • 1 ¼ cups (125 g) quick oats (see note)
  • 1 ¼ cups (125 g) old-fashioned oats (see note)
  • 1 cup (170 g) chocolate chips
  • 1 cup (170 g) butterscotch chips or peanut butter chips or more chocolate chips (see note)

Instructions 

  • 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!

Notes

Oats: I like the combo of the two different kinds of oats, but you can use either all quick oats or all old-fashioned oats (slightly different texture in the bars if doing so).
Peanut Butter: I have not tried these bars with natural peanut butter or a different kind of nut butter like cashew or almond.
Gluten-Free: these bars are easily gluten-free since there isn't flour in the recipe, but to be truly gluten-free, double check all your ingredients (particularly the oats and the butterscotch or other chips) to ensure the package clearly states they are gluten-free. The Nestle brand of butterscotch chips are NOT gluten-free but the Guittard and Hershey brands are gluten-free.