Peanut Butter Banana Oatmeal Cookie Sandwiches
Cook time
Total time
Serves: 30 sandwiches or 60 cookies
  • 1 cup unsalted butter, room temperature
  • ⅓ cup chunky or creamy peanut butter (I prefer to use chunky)
  • 1 cup granulated sugar
  • 1 egg, room temperature
  • ¾ teaspoon vanilla extract
  • 3 medium ripe bananas, mashed
  • 1½ cup all-purpose flour
  • 1¾ cup rolled old-fashioned oats
  • ½ teaspoon baking soda
  • 1 teaspoon cinnamon
  • 1 teaspoon kosher salt
  • ½ teaspoon nutmeg
  • 1 cup creamy peanut butter
  • ½ cup marshmallow fluff
  • ½ cup powdered sugar, plus more as needed
  • 1 teaspoon vanilla extract
  • 4 tablespoons milk, plus more as needed
  1. Preheat your oven to 350 degrees F. Beat together the butter, peanut butter, and sugar, until light and fluffy, about 3-5 minutes. Beat in the egg and vanilla extract until just combined.
  2. Whisk together the flour, oats, baking soda, cinnamon, nutmeg, and salt. Add in ⅓ of the flour mixture to the wet ingredients and mix until combined. Add in ½ of the banana mixture and mix until combined. Add in another ⅓ of the flour, then the rest of the banana, then the rest of the flour, until everything is just moistened and combined. You want to start and end with the flour.
  3. Grease and/or line two baking sheets and drop spoonfuls (about two teaspoons at a time) onto the sheets. Bake for 10-12 minutes, until golden. Allow to cool completely before turning into sandwiches.
  4. For the frosting, beat together the peanut butter and fluff until combined, then add in the powdered sugar, slowly, a bit at a time, over low speed. Add in the vanilla and then the milk, one tablespoon at a time, until the frosting is spreadable. You may need to adjust the powdered sugar and milk ratio until you have it at a good consistency.
  5. Place a dollop (a teaspoon or two) on one flat side of a small cookie, then smush it together with another cookie, flat side down. Continue to do this until you are out of cookies. Makes 30 sandwiches (about 60 cookies).
Recipe by The Crepes of Wrath at