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Oatmeal Cream Pie Bars

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Oatmeal cream pie bars will remind you of the Little Debbie oatmeal creme pies you used to get in your lunchbox.  These chewy cookie bars are super easy to make and will give you a taste of childhood.

Spatula lifting out first square of oatmeal cream pie bars with chewy molasses and oatmeal cookie layer topped with fluffy white marshmallow fluff buttercream and sprinkles.

These chewy oatmeal cookie bars are rich with deep molasses flavor and topped with marshmallow fluff buttercream for the perfect treat.  These bars come together super quickly, and can be in the oven in under 10 minutes.

Then a quick marshmallow fluff frosting layer is spread over to make them out of this world good.  They are just like those Little Debbie treats we all grew up on!

If these don’t bring back childhood memories of sack lunches, I don’t know what will.  Actually, to tell you the truth I am not sure that I frequently had these in my lunch box.  

Ingredients including butter, brown sugar, flour, oatmeal, eggs, molasses, vanilla, salt, cinnamon, and baking powder ready to be made into oatmeal creme pie bars.

I seem to think I ate school lunch most of the time.  Though I do know that when I was older, my mom always had a treat basket for my younger siblings’ lunches.

They seemed to bring cold lunch more often and they got to pick one item from the treat basket for their lunch box.  Of course the treats were the best part of the lunch packing (and eating) experience!

Why You’ll Love These Cookie Bars

These cookie bars are easy to make.  You don’t have to worry about them spreading, so you can start with melted butter and soft dough.

You can mix it by hand with no problem, no need to pull out the stand mixer or anything! Just spread it, bake it and load it with frosting!

There is the warm depth of molasses and just a slight cinnamon spice.  It is a great compliment to the marshmallow fluff buttercream frosting.

In fact, the molasses and creamy frosting combine to make almost a caramel flavor.  And the chew of the cookie is so good.

I originally shared this recipe here on the site back in 2016.  I made them for a football party and they were a hit.

But most of you didn’t know I existed back in 2016 and I have been dreaming of these bars for the past couple of months.  So I whipped some up, shot some new pictures and a video and added a printable recipe card so you could more easily make them too.

And I really hope you do.  These went with me to family dinner and everyone kept going back for a little more.  

They also lead to a lot of fun conversation about our favorite packaged treats.  What are your favorite convenience treats?

It would be fun to make more copycat versions of stuff.  Just let me know what you’d like and we’ll see what we can come up with!

Frequently Asked Questions

Can I use old fashioned oats instead of instant?

If you only have old fashioned oats in your pantry, go ahead and use them. The texture of the oatmeal cream pie cookie bars may be slightly chewier, but they will still be delicious.

What is the filling for oatmeal cream pies?

The rich molasses oatmeal cookies are sandwiched around a layer of creamy vanilla frosting. We think our marshmallow fluffy frosting does a good job of mimicking that flavor and texture.

Storing Oatmeal Cookie Bars

These cookie bars can be stored at room temperature for a couple of days.  They are at their chewy best when stored at room temperature.

For longer storage, refrigerate in an airtight container for up to a week.  Or freeze them for up to three months.

fork taking bite of oatmeal cookie bar with marshmallow fluff buttercream.

If you chill them until the frosting is set, you can stack them for storage.  But I would but them in a single layer to defrost them.

My guess is they won’t last that long anyway.  They are super tasty and hard to stay out of once you dig in!

More fun cookie bar recipes

If you are a fan of soft and delicious cookie bars, you may want to check out my recipe for soft sugar cookie bars.  I topped mine with a chocolate frosting and plenty of sprinkles for a fun treat!

Or for a fun fall flavored treat, make some pumpkin spice cookie bars.  They are another fabulous option to go with the marshmallow fluff buttercream!

Square of homemade oatmeal creme pie bars with marshmallow fluff buttercream on small dessert plate, ready to be eaten.

Pecan pie bars are another fun bar treat. They are built on a shortbread crust and have a simple but tasty pecan topping.

Love this recipe? Give it a ⭐⭐⭐⭐⭐ review in the recipe card below!

Spatula lifting out first square of oatmeal cream pie bars with chewy molasses and oatmeal cookie layer topped with fluffy white marshmallow fluff buttercream and sprinkles.

Oatmeal Cream Pie Bars

Servings: 24 Servings
Author: Carlee
These fun cookie bars will remind you of the oatmeal creme pies you used to get in your lunchbox.  They are super easy to make and will give you a taste of childhood!
4.91 from 30 ratings
Prep Time 10 minutes
Cook Time 30 minutes
Total Time 40 minutes


Molasses Oatmeal Cookie Bars

  • 1 cup butter melted
  • 2 cups light brown sugar packed
  • 4 Tablespoons molasses
  • 1 Tablespoon vanilla extract
  • 2 large eggs
  • 1 teaspoon ground cinnamon
  • ½ teaspoon salt
  • 2 cups instant oats
  • cups all-purpose flour
  • 1 teaspoon baking powder

Marshmallow Fluff Buttercream

  • 1 cup butter softened
  • 2 cups powdered sugar
  • 1 teaspoon vanilla extract
  • 7 ounces marshmallow fluff
Makes: 10 x 15inch rectangle1inch height


Oatmeal Cookie Bars

  • Preheat oven to 350°F and grease a 10×15-inch bar pan.
  • Stir together butter, brown sugar, molasses, and vanilla.
    1 cup butter, 2 cups light brown sugar, 4 Tablespoons molasses, 1 Tablespoon vanilla extract
  • Add eggs and mix well.
    2 large eggs
  • In another bowl, stir together dry ingredients.
    1 teaspoon ground cinnamon, ½ teaspoon salt, 2 cups instant oats, 1½ cups all-purpose flour, 1 teaspoon baking powder
  • Add dry ingredients to wet ingredients, stirring until just combined.
  • Spread in prepared pan and bake for 25-30 minutes or until set.
  • Allow to cool completely before frosting.

Marshmallow Fluff Buttercream

  • In mixing bowl, beat butter until light and fluffy.
    1 cup butter
  • Add remaining ingredients and mix on medium speed for 4 minutes.
    2 cups powdered sugar, 1 teaspoon vanilla extract, 7 ounces marshmallow fluff
  • Spread over cooled bars. Decorate with sprinkles if desired.
  • Cut into squares and enjoy.



Serving: 1ServingCalories: 341kcalCarbohydrates: 48gProtein: 3gFat: 16gSaturated Fat: 10gPolyunsaturated Fat: 1gMonounsaturated Fat: 4gTrans Fat: 1gCholesterol: 56mgSodium: 201mgPotassium: 117mgFiber: 1gSugar: 35gVitamin A: 495IUVitamin C: 0.003mgCalcium: 44mgIron: 1mg

Nutritional Disclaimer

“Cooking With Carlee” is not a dietitian or nutritionist, and any nutritional information shared is an estimate. If calorie count and other nutritional values are important to you, we recommend running the ingredients through whichever online nutritional calculator you prefer. Calories and other nutritional values can vary quite a bit depending on which brands were used.

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Recipe Rating


Wednesday 17th of January 2024

Would these taste good with just a buttercream frosting?


Thursday 18th of January 2024

Yes, they would be good with your favorite buttercream.

Barb A. J.

Monday 15th of January 2024

These look and sound delicious. We love the store bought ones. It is a childhood wonderful memory. I’m going to try making these tomorrow. My sister will love them too. We are both in our 70’s, but we still remember enjoying Oatmeal Cookies. Thanks for the memories and for this recipe.


Monday 15th of January 2024

Thank you so much. I hope you love them and I hope they bring back those tasty childhood memories!


Sunday 30th of August 2020

where is the marshmallow buttercream recipe? The link takes you to a blog page and no recipes. Thanks


Sunday 30th of August 2020

Thanks for letting me know. The link should be fixed now, sorry for the trouble.


Friday 21st of August 2020

Looking forward to try these bars. How do I Pin?


Saturday 29th of August 2020

There are buttons at the top and bottom of the post, otherwise you can click the little v shape with the dots on it by the teal heart. I hope that helps!

Andrea Nine

Friday 14th of August 2020

These look absolutely divine! My family loves oatmeal cream pies so I think they would be over the moon for these! Have a beautiful weekend!


Saturday 29th of August 2020

They are sooooooooo good! Thank you!