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Oatmeal Cream Pie Bars

A nostalgic and highly convenient bar version of the classic childhood treat. Chewy, spiced oatmeal cookie base topped with a fluffy, authentic marshmallow cream frosting.
Print Recipe
Prep Time 20 minutes
Cook Time 22 minutes
Total Time 42 minutes
Servings: 15 bars
Course: Dessert, Snack
Cuisine: American
Calories: 415
Ingredients Equipment Method Notes

Ingredients
  

Chewy Oatmeal Base
  • 1 cup unsalted butter softened to room temperature
  • 1 cup dark brown sugar packed
  • 0.5 cup granulated sugar
  • 1 tablespoon molasses unsulfured
  • 2 large eggs room temperature
  • 2 teaspoons pure vanilla extract
  • 1.5 cups all-purpose flour
  • 3 cups quick-cooking oats do not use old-fashioned oats
  • 1 teaspoon baking soda
  • 1.5 teaspoons ground cinnamon
  • 0.25 teaspoon ground nutmeg
  • 0.5 teaspoon kosher salt
Marshmallow Cream Frosting
  • 0.75 cup unsalted butter softened to room temperature
  • 1.5 cups powdered sugar sifted
  • 1 cup marshmallow fluff marshmallow creme
  • 1 teaspoon pure vanilla extract
  • 1 pinch salt

Equipment

  • 9x13 inch baking pan
  • Stand mixer or hand mixer
  • Mixing bowls

Method
 

  1. Preheat oven to 350°F (175°C). Line a 9x13 inch baking pan with parchment paper, leaving an overhang for easy removal. Spray lightly with non-stick spray.
  2. In a medium bowl, whisk together the flour, quick oats, baking soda, cinnamon, nutmeg, and kosher salt. Set aside.
  3. In a large bowl, beat 1 cup softened butter, dark brown sugar, and granulated sugar until light and fluffy (about 2-3 minutes).
  4. Add the molasses and vanilla extract, mixing until combined. Beat in the eggs one at a time, scraping down the bowl as needed.
  5. Gradually add the dry oat mixture to the wet ingredients on low speed. Mix just until combined. Do not overmix.
  6. Press the dough evenly into the prepared baking pan. Bake for 18-22 minutes until edges are golden and the center is set. Do not overbake.
  7. Place the pan on a wire rack and let the bars cool completely before frosting.
  8. To make the frosting: Beat 3/4 cup softened butter until creamy. Slowly add powdered sugar and beat until smooth. Add marshmallow fluff, vanilla, and a pinch of salt. Beat on medium-high for 2-3 minutes until light and fluffy.
  9. Spread the frosting evenly over the completely cooled oatmeal bars. Use the parchment sling to remove from the pan, slice into squares, and serve.

Notes

Store leftover bars in an airtight container at room temperature for up to 4 days. Freezing instructions are included in the post.