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bite taken out of a loaded peanut butter christmas cookie bar
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Loaded Peanut Butter Christmas Cookie Bars

Loaded Peanut Butter Christmas Cookie Bars are packed full of peanut butter flavor and all your favorite mix-ins. Holly Jolly deliciousness for your holiday party, ready in under an hour!
Course Dessert
Cuisine American
Prep Time 25 minutes
Cook Time 30 minutes
Total Time 55 minutes
Servings 24 bars
Author Tessa Arias

Ingredients

  • 2 ½ cups (286 grams) all-purpose flour, measured correctly
  • 1 teaspoon baking powder
  • ¼ teaspoon baking soda
  • ¾ teaspoon fine sea salt
  • 1 stick (113 grams) unsalted butter, at cool room temperature
  • 1 cup (270 grams) creamy peanut butter
  • 1 cup (200 grams) packed light brown sugar
  • 3/4 cup (150 grams) granulated sugar
  • 2 large eggs, at room temperature
  • 1 ½ tablespoons vanilla extract
  • 1 tablespoon milk
  • 1 cup (170 grams) peanut butter chips
  • 1 cup (185 grams) holiday Peanut Butter M&Ms + heavy ⅓ cup (70 grams), to decorate
  • 1 cup (170 grams) semisweet chocolate chips + ⅛ cup (21 grams), to decorate
  • Flaky sea salt, for topping, optional

Instructions

  • Preheat the oven to 350°F. Line a 9x13 metal baking pan with aluminum foil, using metal binder clips to keep foil in place. Spray sides and bottom of pan generously with cooking spray. Set aside.
  • In a medium bowl, combine the flour, baking powder, baking soda, and salt. Set aside.
  • In the bowl of an electric mixer fitted with the paddle attachment, beat the butter, peanut butter, brown sugar, and granulated sugar on medium-high speed until very well combined, about 2 minutes. Scrape down the sides and bottom of the bowl. Add the eggs, vanilla, and milk and beat until combined.
  • On low speed, gradually add the flour mixture and beat until just combined. Dough will be thick. Add the peanut butter chips, M&Ms, and chocolate chips and mix until just combined. You may need to do this by hand with a spatula if your mixer isn’t strong enough.
  • Remove the dough to the prepared pan, pressing into the pan evenly. Sprinkle with the reserved M&Ms and chocolate chips. Bake for about 30 minutes, or until the center is golden brown and just slightly jiggly. Sprinkle with flaky sea salt. Place pan on a wire rack and let cool completely before cutting into squares and serving.
  • Store bars in an airtight container at room temperature for up to 5 days.

Notes

Don’t use a glass pan here as it can dry out the edges of your bars before the middle can bake through. Learn more about Glass vs. Metal Baking Pans here.