Description
Delicious Oatmeal Cream Pie Bars featuring a perfectly baked oatmeal cookie base layered with a fluffy marshmallow cream filling. These bars offer the nostalgic flavors of oatmeal cream pies in a convenient bar form, combining chewy oats and spiced cookie with a sweet, creamy filling. Perfect for dessert or an indulgent snack.
Ingredients
Scale
For the Oatmeal Cookie Bars
- 1¼ cups unsalted butter (283 grams, 2½ sticks)
- ¾ cup dark brown sugar (firmly packed)
- ½ cup granulated sugar (100 grams)
- 2 large eggs (100 grams)
- 1 teaspoon pure vanilla extract (4 grams)
- 1½ cups all-purpose flour (180 grams)
- 1 teaspoon baking soda (6 grams)
- 1 teaspoon ground cinnamon (3 grams)
- ¼ teaspoon ground nutmeg
- ¾ teaspoon kosher salt
- 1½ cups old-fashioned oats (150 grams, uncooked)
- 1½ cups quick oats (134 grams, uncooked)
For the Cream Filling
- ¾ cup unsalted butter (170 grams, 1½ sticks), softened
- 2 cups powdered sugar (226 grams)
- 13 ounces marshmallow fluff (369 grams, 1 jar)
- 1½ teaspoons pure vanilla extract (6 grams)
- ¾ teaspoon kosher salt
Instructions
- Preheat and Prepare Pans: Preheat your oven to 375°F (190°C). Spray two 8×12-inch baking pans with nonstick spray. If you only have one 12×16-inch pan, line it with parchment paper leaving a 2-inch overhang on all sides and spray the parchment with nonstick spray. This helps with easy removal later.
- Cream Butter and Sugars: In a stand mixer fitted with the paddle attachment, beat together the unsalted butter and both sugars until the mixture is creamy and smooth. Add the eggs and vanilla extract and continue beating until well combined.
- Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking soda, cinnamon, nutmeg, and kosher salt. Add all of this dry mixture to the butter mixture at once, beating only until just incorporated to avoid overmixing.
- Add Oats: Fold in both the old-fashioned and quick oats into the batter until fully combined, creating a thick, sticky dough.
- Divide and Spread Dough: Divide the dough evenly between the prepared pans. Spray a wooden spoon, rubber spatula, or your fingers with cooking spray to prevent sticking, then press the dough out evenly across each pan to the edges.
- Bake Cookie Bars: Bake the dough in the preheated oven for 12-13 minutes or until the centers are cooked through and the edges are light golden brown. Be careful not to overbake to keep the bars moist.
- Make Cream Filling: While the bars bake, prepare the filling. Using a stand mixer with a whisk attachment, beat the softened butter until fluffy. Gradually add the powdered sugar and beat until light in color and smooth. Add marshmallow fluff, vanilla extract, and salt, then continue beating until the filling is light, fluffy, and well combined. Set aside.
- Cool Bars: Transfer the baked bars to a cooling rack and cool for about 10 minutes in the pans. Then carefully lift them out by the parchment paper edges and return to the cooling rack to cool completely.
- Assemble Bars: Once fully cooled, place one uncut oatmeal cookie bar on a large tray. Spread the cream filling evenly over it. Remove parchment paper from the second bar and place it on top of the filling, pressing gently to sandwich the layers together. Wrap the assembled cookie in plastic wrap and cover with foil.
- Freeze and Cut: Freeze the layered cookie for at least 2 hours or overnight to set the filling and make cutting easier. Once frozen, cut the large cookie into 18 bars. Serve chilled or at room temperature.
Notes
- Using two 8×12 pans is ideal, but a single 12×16 pan with slightly less dough also works.
- Spraying tools and fingers with cooking spray helps to handle the sticky dough easily.
- Do not overbake the cookie bars; they should be light golden and moist inside.
- Freezing the assembled bars before cutting keeps the cream filling stable and makes cutting neat.
- Store bars in an airtight container in the refrigerator for up to 5 days or freeze for longer storage.
