Homemade Oatmeal Cream Pie Bars (Copycat Recipe)

By Becky Hardin

Published Feb 1, 2018

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These Homemade Oatmeal Cream Pies are an adult version of one of my favorite childhood snacks. I’ve prepared these copycat bars so they feature two layers of perfectly chewy oatmeal cookies with a layer of homemade marshmallow cream icing sandwiched between. These are super easy to make—the hardest part is waiting for them to chill long enough to cut into squares!

The Best Oatmeal Cream Pies

Oatmeal Creme Pies were invented by Little Debbie. It was the very first snack the company created, back in the 1960s, and it’s been a classic childhood favorite ever since.

As a kid, one of my very favorite indulgences was these oatmeal cream pies. There was just something about those soft oatmeal cookies holding in that decadent marshmallow cream. I would crave this special flavor time and time again, so I knew I needed to recreate it in bar form. My mom helped me perfect this recipe for oatmeal cream pie bars, and I couldn’t be more excited. The cookies are the perfect consistency, chewy but substantial enough to keep their form. And let me tell you, the cream filling is to die for; I cannot be trusted alone with it. I love serving these bars for a snack or when I’m entertaining.

Another childhood favorite is this old-fashioned oatmeal cake, soft, moist, and mildly spiced; it’s a true classic in my family.

Tips for Beginners

• Use an electric mixer. It makes quick work of the batter and ensures all the ingredients blend together evenly. Mixing everything by hand takes more effort and can leave you with an unevenly mixed batter.
• Serve cold for the best experience. You can serve them cold or at room temperature, but I find they get a bit messy when too warm.
• For the classic round shape. Scoop and bake the dough as individual cookies, then assemble. If you prefer to make bars, trim off the corners to create a round shape.
• Instead of 2 8×12 pans. If you don’t have two 8×12 pans, use one 12×16-inch pan. Use 1 cup less dough so the bars don’t end up too thick.

Recipe Card

Oatmeal Cream Pie Bars

Difficulty: Easy

4.50 from 28 votes

Prep: 10 minutes mins

Cook: 13 minutes mins

Freeze Time: 2 hours hrs

Total: 2 hours hrs 23 minutes mins

Servings: 18 bars

Author: Becky Hardin

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These copycat Oatmeal Cream Pie Bars have a layer of homemade marshmallow cream sandwiched between two perfectly chewy oatmeal cookies, all in bar form.

Step-by-step photos can be seen below the recipe card.

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Ingredients 

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For the Bars

• ▢ 1¼ cups unsalted butter 283g (2½ sticks)
• ▢ ¾ cup dark brown sugar firmly packed
• ▢ ½ cup granulated sugar 100g
• ▢ 2 large eggs 100g
• ▢ 1 tsp pure vanilla extract 4g
• ▢ 1½ cups all-purpose flour 180g
• ▢ 1 tsp baking soda 6g
• ▢ 1 tsp ground cinnamon 3g
• ▢ ¼ tsp ground nutmeg .5g
• ▢ ¾ tsp kosher salt 2-3g
• ▢ 1½ cups old-fashioned oats 150g, uncooked
• ▢ 1½ cups quick oats 134g, uncooked

For the Cream Filling

• ▢ ¾ cup unsalted butter 170g, (1½ sticks)
• ▢ 2 cups powdered sugar 226g
• ▢ 13 oz. marshmallow fluff 369g (1 jar)
• ▢ 1½ tsp pure vanilla extract 6g
• ▢ ¾ tsp kosher salt 5-6g

Video

Instructions 

• Preheat oven to 375°F and spray two 8×12-inch baking pans with nonstick spray. Line the pans with parchment so that each edge of the pan has a 2-inch over-flap. Spray the parchment with nonstick cooking spray.
• In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugars together until creamy. Add eggs and vanilla and beat well.
  1¼ cups unsalted butter, ¾ cup dark brown sugar, ½ cup granulated sugar, 2 large eggs, 1 tsp pure vanilla extract
• In a medium bowl, whisk the flour, baking soda, cinnamon, nutmeg, and salt together. Add the flour mixture to the wet mixture all-at-once and beat only until flour mixture is incorporated.
  1½ cups all-purpose flour, 1 tsp baking soda, 1 tsp ground cinnamon, ¼ tsp ground nutmeg, ¾ tsp kosher salt
• Add the oats and mix until incorporated.
  1½ cups old-fashioned oats, 1½ cups quick oats
• Divide the dough in half and spread half in each pan. Spray a wooden spoon or rubber spatula with cooking spray to prevent the dough from sticking. Work the dough until it reaches across the pans evenly. (If necessary, spray your fingers with cooking spray and spread the dough with your fingers. The dough is somewhat stiff and sticky).
• Bake 12-13 minutes, or until the dough is cooked in the middle and is light golden brown. Do not over-bake or the bars will dry out.
• While the bars bake, make the cream filling: In the bowl of a stand mixer fitted with the whisk attachment, beat the softened butter until fluffy. Add the powdered sugar and beat until lighter in color and smooth. Add the marshmallow fluff, vanilla, and salt. Beat until light and fluffy. Set aside until ready to use.
  ¾ cup unsalted butter, 2 cups powdered sugar, 13 oz. marshmallow fluff, 1½ tsp pure vanilla extract, ¾ tsp kosher salt
• Transfer the cookie bars to a cooling rack to cool 10 minutes. Lift the bars out of the pans, by the parchment paper and set them back on the cooling rack to completely cool.
• When bars are cool, spread the cream filling over one of the uncut 8×12-inch cookies. Remove the parchment paper and place the other 8×12-inch cookie over the cream filling and press gently down. Place the entire large cookie on a larger baking tray and cover it with plastic wrap and foil. The cookies are easy to cut when frozen. Place in the freezer for at least 2 hours or overnight.
• Cut the frozen cookie into bars.

Equipment

• Kitchen Scale (optional)
• 2 8×12-inch Baking Pan
• Stand Mixer

Becky’s Tips

• Using an electric mixer ensures everything gets well incorporated.  
• I find these bars get messy when too warm, so I serve them cold.
• Make cookies instead of bars if you prefer a round shape.
• Use one 12×16-inch pan, and use 1 cup less dough if you don’t have 2 8×12 pans.
• Store in an airtight container in the refrigerator for up to 4 days.

Serving: 1barCalories: 450kcalCarbohydrates: 63gProtein: 4gFat: 22gSaturated Fat: 13gPolyunsaturated Fat: 1gMonounsaturated Fat: 6gTrans Fat: 1gCholesterol: 75mgSodium: 269mgPotassium: 87mgFiber: 2gSugar: 40gVitamin A: 661IUVitamin C: 0.01mgCalcium: 27mgIron: 1mg

Nutrition information is automatically calculated, so should only be used as an approximation.

Did you make this? Leave a comment!

How to Make Oatmeal Cream Bars Step by Step

Get the oven going, prepare the pans, and cream the butter, sugar, and eggs: Preheat the oven to 375°F, spray two 8×12-inch baking pans with nonstick spray, and line them with parchment paper. Spray the parchment with nonstick cooking spray so the dough doesn’t stick. In the bowl of a stand mixer fitted with the paddle attachment, cream 1¼ cups butter, ¾ cup dark brown sugar, ½ cup granulated sugar, 2 eggs, and 1 tsp vanilla extract.

Combine the dry ingredients: In a medium-sized bowl, whisk 1½ cups all-purpose flour, 1 tsp baking soda, 1 tsp ground cinnamon, ¼ tsp ground nutmeg, and ¾ tsp kosher salt.

Add dry mixture to the wet mixture.

Add the oats: Add 1½ cups old-fashioned oats and 1½ cups quick oats.

Portion the dough and bake: Divide the dough in half and spread into each pan. Use a wooden spoon sprayed with cooking spray to smooth the dough out so it covers each pan evenly.

Bake for 12-13 minutes, or until the dough is cooked in the middle and light golden brown. Do not over-bake, or the bars will dry out.

Make the filling: In the bowl of a stand mixer fitted with the whisk attachment, beat ¾ cup of softened butter until fluffy. Add 2 cups powdered sugar and beat until the mixture gets lighter in color and smooth. Add 13 oz. of marshmallow fluff,  1½ tsp vanilla, and ¾ tsp salt and beat until light and fluffy. Set aside until ready to use.

Let the cookie bars sit on a cooling rack for 10 minutes. Lift the bars out of the pans and set them directly on the cooling rack to cool completely.

Layer: Spread the cream filling over one of the uncut cookie bars. Remove the other cookie dough from the parchment paper, place the cookie dough on top of the cream filling, and press down gently. Place the entire large cookie on a larger baking tray and cover it with plastic wrap and foil. Place in the freezer for at least 2 hours or overnight so they are easier to cut.

Cut and serve: Cut the frozen cookie into bars. Serve and enjoy.

How to Store

Place the bars in an airtight container and store them in the fridge for up to 4 days.

Freeze

Freeze leftovers for up to 3 months. Thaw in the fridge overnight.

Serving Suggestions

I like serving these oatmeal cream bars for dessert or an afternoon snack. I find they go well with a steaming hot pumpkin spice latte or a cup of this banana bread latte. For the kids, I’ll prepare oat milk or a refreshing homemade lemonade. This recipe makes about 18 bars, depending on how big you cut the squares, so it’s great for serving a crowd.

More Copycat Desserts

• These Copycat Hostess Cupcakes feature rich, chocolate cupcakes, filled with marshmallow creme, topped with chocolate ganache and the iconic white swirl.
• Copycat McDonald’s Strawberry Cream Pie is a flaky little pocket of strawberries and cream cheese.
• Copycat Pepperidge Farm Milano Slices Cookies feature sweet, minty, chocolate topped slices.

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