Oatmeal cream pie bars will remind you of the Little Debbie oatmeal creme pies you used to get in your lunchbox. The chewy oatmeal cookie base is topped with a marshmallow fluff frosting. The combination is a delicious taste of nostalgia.
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.
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.
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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!
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.
Oatmeal Cream Pie Bars
Ingredients
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
- 1½ 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
Instructions
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.
Notes
Video
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Would these taste good with just a buttercream frosting?
Yes, they would be good with your favorite buttercream.
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.
Thank you so much. I hope you love them and I hope they bring back those tasty childhood memories!
where is the marshmallow buttercream recipe? The link takes you to a blog page and no recipes. Thanks
Thanks for letting me know. The link should be fixed now, sorry for the trouble.
Looking forward to try these bars. How do I Pin?
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!