Oatmeal Cream Pie Bars Recipe — Chewy, Cream-Filled Dessert Bars

Oatmeal Cream Pie Bars recreate the classic Oatmeal Creme Pie: marshmallow cream sandwiched between two soft, chewy oatmeal cookie layers. These sandwich cookie bars are simple to make and perfect when you want the flavor of a homemade treat without forming individual cookies.

Cookie bars save time compared to rolling, scooping and baking dozens of individual cookies. Instead of shaping each sandwich cookie one-by-one, this recipe uses two 9×13 pans so you can bake two cookie layers at once, then assemble them with the marshmallow cream filling.

OATMEAL CREAM PIE BARS

Begin by preparing an oatmeal cookie dough using both quick and old-fashioned oats for the best texture. Divide the dough between two parchment-lined 9×13 pans and bake until lightly golden. After the layers cool, whip a filling from marshmallow fluff, butter and powdered sugar. Spread the filling over one cookie layer, top with the second layer, chill until firm, then slice into bars.

Ingredients in Oatmeal Cream Pie Bars

OATMEAL COOKIE LAYERS

Butter – Use real butter softened to room temperature for best texture.

Sugars – A combination of brown sugar and granulated sugar adds depth and chew.

Vanilla extract – Good vanilla improves flavor.

Eggs – Two large eggs bind the dough.

Flour – All-purpose flour works well; a gluten-free substitute can be used if needed.

Cinnamon – Adds warm spice that complements the oats.

Salt – Enhances overall flavor.

Baking soda – Provides lift; ensure it’s fresh.

Oats – A mix of quick oats and old-fashioned oats creates the ideal texture.

MARSHMALLOW CREAM FILLING

Butter – Room-temperature butter, salted or unsalted depending on preference.

Powdered sugar – Keeps the filling smooth and sweet.

Marshmallow cream – Also called marshmallow fluff; gives the filling its signature texture.

Vanilla extract – A touch of vanilla rounds out the filling.

HOW TO MAKE OATMEAL CREAM PIE BARS

Preheat the oven to 350°F. Line two 9×13 baking dishes with parchment paper and lightly spray them with nonstick cooking spray so the bars lift out easily.

MAKE THE OATMEAL COOKIE LAYERS

Cream the butter, brown sugar and granulated sugar together with a hand mixer until light and creamy, about 2–3 minutes.

Add the eggs and vanilla, then beat another 2–3 minutes until well combined.

In a separate bowl, whisk together the flour, cinnamon, salt and baking soda. Add the dry mixture to the wet ingredients and mix just until combined. Stir in both quick oats and old-fashioned oats until evenly incorporated.

Divide the dough evenly between the two prepared pans. Spray your hands with nonstick cooking spray and press the dough to the corners so each pan has an even layer.

Bake the layers for about 13 minutes, or until the edges are a light golden brown. Remove from the oven and let cool completely before assembling.

MAKE THE CREAM FILLING

Beat the softened butter until light and fluffy, then add the powdered sugar and mix until smooth. Fold in the marshmallow fluff and vanilla, beating until the filling is uniform and spreadable.

Make sure the cookie layers are completely cool. Lift one layer from its pan using the parchment paper and place it on a tray. Spread the marshmallow filling evenly over that layer. Lift the second layer from its pan and carefully invert it on top of the filling. Press gently to adhere.

Chill the assembled bars in the freezer for 1 hour to firm the filling, then slice into bars and serve.

TIPS FOR MAKING THE BEST COOKIE BARS

• Do not use melted butter; it should be softened to room temperature for proper texture.
• Cream butter and sugars for 2–3 minutes to improve the cookie’s consistency and chew.
• Always preheat the oven so the bars bake evenly.
• Line pans with parchment paper to make removing and assembling the bars much easier.
• Avoid overbaking. Remove the bars when the edges are just turning light golden brown for soft, chewy results.

HOW DO YOU SOFTEN BUTTER?

To soften butter quickly, use the defrost setting on your microwave. Keep the butter in its wrapper or place the measured amount in a bowl. Run the defrost function for about 20 seconds, then press with a rubber spatula to test. If it doesn’t yield, heat an additional 5–10 seconds, watching carefully so it doesn’t melt.

How to store Oatmeal Cream Pie Bars?

Store the bars in an airtight container in the refrigerator for up to 4–5 days. They keep better chilled, though allowing them to sit at room temperature for 30–45 minutes before serving brings out the flavor and softens the filling.

HOW TO CUT PERFECT COOKIE BARS

Using parchment paper makes cutting and removing bars easy. Lift the entire slab from the pan, place it on a cutting board and slice with a sharp knife for clean, uniform bars. Chilling before cutting helps achieve neater edges.

LIKE COOKIE BARS? TRY THESE RECIPES

• Strawberry Cheesecake Cookie Bars
• Snickerdoodle Cookie Bars
• Sugar Cookie Bars
• Chocolate Chip Cookie Bars
• No Bake Cookie Bars
• Oatmeal Chocolate Chip Cookie Bars
• Lemon Sugar Cookie Bars
• Swirled Patriotic Cookie Bars
• Fudgy Oatmeal Cookie Bars
• Twix Cookie Bars
• Easy Peanut Caramel Cookie Bars
• Gingerbread Cookie Bars
• Butterscotch Pretzel Cookie Bars
• Reese’s Cookie Bars
• S’mores Cookie Bars
• Oreo Cookie Bars

Oatmeal Cream Pie Bars are an easy, crowd-pleasing dessert that captures the nostalgic flavor of classic cream-filled oatmeal cookies while saving time with a simple bake-in-pan method.