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Oatmeal M&M Peanut Butter Skillet Cookie


  • 1/3 cup 6 tablespoons unsalted butter, softened
  • ¾ cup light brown sugar
  • 1 teaspoon vanilla extract
  • 3/4 cup creamy peanut butter (divided)
  • 1 large egg
  • ½ cup old-fashioned rolled oats
  • ¾ cup all-purpose flour
  • ½ teaspoon baking powder
  • ½ teaspoon baking soda
  • ¼ teaspoon salt
  • ½ cup chocolate chips
  • ½ cup M&Ms (I used peanut)


  1. Grease a 6-inch or 8-inch cast iron skillet with butter. Set aside.
  2. In a large bowl, cream together butter and brown sugar until light and fluffy. Beat in 1/4 cup peanut butter and vanilla extract. Whisk in the egg until well blended.
  3. Stir in the oats, flour, baking powder, baking soda, and salt.
  4. Fold in chocolate chips and M&Ms. Chill cookie dough, covered, at least 2 hours and up to 3 days.
  5. Press about ⅓ of the dough into the bottom of prepared skillet (the entire bottom and sides of the skillet should be covered with dough). Fill with 1/2 cup peanut butter. Top with more dough until the top is completely covered and the peanut butter is sealed inside. Garnish with extra chocolate chips and M&Ms if desired. Cover with foil and refrigerate for at least 30 minutes, or up to 3 days.
  6. When you’re ready to bake, preheat oven to 350ºF.
  7. Bake for 25-30 minutes or until golden brown on top. Serve immediately with ice cream.