Classic Oatmeal Creme Pie Bars
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Remember those soft, chewy oatmeal creme pies from your lunchbox days? These homemade Oatmeal Creme Pie Bars are that exact nostalgic treat, only thicker, softer, and loaded with a fluffy marshmallow creme filling. You get a tender oatmeal cookie bar base with warm cinnamon on the bottom and a sweet, pillowy marshmallow layer on top. It’s all the childhood magic in an easier, sliceable form, and one bite takes you right back!
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Why You’ll Love These Oatmeal Creme Pie Bars
- Soft, chewy, and tender: The oatmeal cookie base bakes up thick and melt-in-your-mouth soft, just like the Little Debbie snack cakes you grew up on. So good.
- Easier than sandwich cookies: No scooping dozens of cookies, no rolling, no matching up pairs. You bake one big pan, spread on the filling, and slice. Done!
- That dreamy marshmallow creme filling: Fluffy, sweet, and light as a cloud. It’s the part everyone fights over, and I won’t judge if you sneak a spoonful straight from the bowl.
- Pure nostalgia: These taste just like the little wrapped ones from your childhood, only better because they’re homemade and twice as thick. If you love that retro snack cake vibe, check out these comfort snack cakes too!
- Thick or thin, your call: Bake them in a small pan for ultra-thick bakery-style bars or a bigger pan for classic thin oatmeal cookie bars.
Ingredients You’ll Need
Warm baking spices, good oats, and a marshmallow filling that adds that cloud‑soft center everyone loves. This oatmeal creme pie recipe delivers everything you remember from the classic snack—soft, chewy oatmeal bars with a buttery base and a marshmallow layer—made with simple pantry ingredients and upgraded for a homemade finish.
For the Oatmeal Cookie Bars
- 1 cup butter, melted and cooled
- 1 ½ cups light brown sugar
- 2 large eggs
- 1 tablespoon vanilla extract
- 1 ¾ cups all-purpose flour
- 1 teaspoon baking soda
- ½ teaspoon baking powder
- 1 teaspoon cinnamon
- ½ teaspoon nutmeg (optional)
- ½ teaspoon salt
- 2 cups old-fashioned oats or quick oats (old-fashioned for chewy, quick oats for softer and more cake-like)
For the Marshmallow Creme Filling
- ½ cup butter, softened
- 1 ½ cups powdered sugar
- 1 cup marshmallow fluff
- 1 teaspoon vanilla extract
- Pinch of salt
How to Make Oatmeal Creme Pie Bars
- Preheat the oven to 350°F. For ultra-thick bars, line an 8×8 or 9×9 pan with parchment paper. Want thinner bars? Use a 9×13 pan instead.
- In a large bowl, whisk 1 cup melted butter and 1 ½ cups brown sugar until glossy.
- Whisk in 2 eggs and 1 tablespoon vanilla.
- Add 1 ¾ cups flour, 1 teaspoon baking soda, ½ teaspoon baking powder, 1 teaspoon cinnamon, ½ teaspoon nutmeg, and ½ teaspoon salt. Mix until just combined, then fold in 2 cups oats.
- Spread the dough evenly into the prepared pan.
- Bake until set: about 26 to 32 minutes for thick 8×8 bars, 22 to 27 minutes for a 9×9 pan, or 18 to 23 minutes for thinner 9×13 bars.
- Let the bars cool completely in the pan. This part matters, so don’t rush it!
- For the filling, beat ½ cup softened butter, 1 ½ cups powdered sugar, 1 cup marshmallow fluff, 1 teaspoon vanilla, and a pinch of salt until light and fluffy.
- Spread the marshmallow filling over the cooled cookie layer.
- Chill for 20 to 30 minutes before slicing for nice clean cuts.
Tips for the Best Oatmeal Cream Pie Bars
- Pick your oats on purpose: Old-fashioned oats give you those chewy, hearty bars (that’s what I used in the photos). Quick oats bake up softer and more like a tender snack cake. Both are delicious, so go with whatever texture you love.
- Cool completely before filling: Warm bars will melt that marshmallow filling right off. Trust me, wait it out, or pop the pan in the fridge to speed things up.
- Want a fluffier filling? Beat in 1 to 2 tablespoons of milk. It loosens things up and makes the marshmallow layer even lighter and creamier.
- Chill for clean slices: These bars cut so much neater when cold. A quick chill firms up the filling and gives you those bakery-sharp edges.
- Sprinkle on some cinnamon sugar: A little dusting over the top before serving adds extra warmth and that nostalgic touch. Such a nice finish. If you can’t get enough cinnamon-and-oat flavor, these soft apple caramel oatmeal cookies are calling your name.
How to Store Oatmeal Creme Pie Bars
- Refrigerator: Store the bars in an airtight container in the fridge for 5 to 6 days. The cold keeps the marshmallow filling set and the cookie layer stays soft and chewy.
- Freezer: Freeze the bars for up to 2 months. Layer them with parchment paper in a freezer-safe container so they don’t stick together. Thaw in the fridge or at room temperature when a craving hits.
- Room temperature: They’re fine out for a few hours if you’re serving them at a party, but the filling gets soft when warm, so the fridge is your friend for longer storage.
Oatmeal Creme Pie Bar Variations
- Choco-Pie twist: Fold a handful of mini chocolate chips into the dough for a chocolatey spin on the classic.
- Firmer filling: Swap the marshmallow creme for a vanilla buttercream if you want a sturdier, less pillowy layer that holds up great for stacking.
- Fall-spiced version: Add a pinch of pumpkin spice to the dough along with the cinnamon for warm autumn flavor. So good when the weather turns cool.
- Extra oaty and hearty: Love that chewy oat texture? Browse these oatmeal cookie makeovers for even more ways to bake with oats.
Oatmeal Creme Pie Bars FAQs
Can I make these oatmeal cream pie bars ahead of time?
Yes! These bars are a great make-ahead treat. Bake and fill them up to 2 days before serving, then keep them covered in the fridge. The flavors settle in beautifully and the texture stays soft.
What’s the difference between old-fashioned oats and quick oats here?
Old-fashioned oats give you chewier, denser bars with more texture. Quick oats bake up softer and more cake-like, closer to the packaged snack cakes. Both work, so it comes down to the texture you prefer.
Do I have to refrigerate oatmeal creme pie bars?
For anything past a few hours, yes. The marshmallow creme filling softens at room temperature, so the fridge keeps it set and keeps the bars fresh for 5 to 6 days.
Can I turn these into sandwich bars instead?
Absolutely. Bake two thinner batches in a 9×13 pan, spread the marshmallow filling over one layer, and top with the second. Chill, then slice into stacked sandwich bars for the full oatmeal creme pie effect.
One bite of these and you’ll understand the hype! Soft, chewy oatmeal cookie bars, a sweet cinnamon warmth, and that fluffy marshmallow creme filling piled on top. It’s everything you loved about the lunchbox original, made bigger, softer, and fresh from your own oven.
Slice these soft and chewy oatmeal bars generously, and keep a batch stashed in the fridge. They bring back all that childhood joy with a homemade upgrade nobody can resist. Time to get baking.
I’d love to see your oatmeal creme pie bars! Tag me on Instagram, share on Pinterest, or connect on Facebook. Happy baking, my sweet friends!
More Nostalgic Treats to Love
- Reese’s Pieces Oatmeal Cream Pie Bars
- Soft Apple Caramel Oatmeal Cookies
- M&M Marshmallow Bars
- Cinnamon Apple Oatmeal Bars
- 10 Tempting Comfort Snack Cakes
Oatmeal Creme Pie Bars
Equipment
- 1 baking pan 8x8, 9x9, or 9x13
- Parchment paper
- large mixing bowls
- Whisk
- Electric mixer
- Spatula
Ingredients
Oatmeal Cookie Bars
- 1 cup butter melted and cooled
- 1 ½ cups light brown sugar
- 2 large eggs
- 1 tablespoon vanilla extract
- 1 ¾ cups all-purpose flour
- 1 teaspoon baking soda
- ½ teaspoon baking powder
- 1 teaspoon cinnamon
- ½ teaspoon nutmeg optional
- ½ teaspoon salt
- 2 cups old-fashioned oats or quick oats
Marshmallow Creme Filling
- ½ cup butter softened
- 1 ½ cups powdered sugar
- 1 cup marshmallow fluff
- 1 teaspoon vanilla extract
- salt Pinch of salt
Instructions
Make the Oatmeal Cookie Bars
- Preheat the oven to 350°F. For ultra-thick bars, line an 8x8 or 9x9 pan with parchment paper. For thinner bars, use a 9x13 pan.
- In a large bowl, whisk 1 cup melted butter and 1 1/2 cups brown sugar until glossy.
- Whisk in 2 eggs and 1 tablespoon vanilla.
- Add 1 3/4 cups flour, 1 teaspoon baking soda, 1/2 teaspoon baking powder, 1 teaspoon cinnamon, 1/2 teaspoon nutmeg, and 1/2 teaspoon salt. Mix until just combined, then fold in 2 cups oats.
- Spread the dough evenly into the prepared pan.
- Bake until set: 26 to 32 minutes for an 8x8 pan, 22 to 27 minutes for a 9x9 pan, or 18 to 23 minutes for a 9x13 pan.
- Let the bars cool completely in the pan.
Make the Marshmallow Creme Filling
- Beat 1/2 cup softened butter, 1 1/2 cups powdered sugar, 1 cup marshmallow fluff, 1 teaspoon vanilla, and a pinch of salt until light and fluffy.
- Spread the filling over the cooled cookie layer.
- Chill for 20 to 30 minutes before slicing for clean cuts.
