Oatmeal Cream Pie Bars

4.50 from 28 votes

These copycat Oatmeal Cream Pie Bars have a layer of homemade marshmallow cream sandwiched between two perfectly chewy oatmeal cookies, all in bar form.

Prep Time10

Cook Time13

Freeze Time2

Total Time2 23

Course: Dessert

Cuisine: American

Difficulty: Easy

Servings: bars

Author: Becky Hardin

Equipment

Kitchen Scale (optional)
2 8x12-inch Baking Pan
Stand Mixer

Ingredients

For the Bars

1¼ cups unsalted butter 283g (2½ sticks)
¾ cup dark brown sugar firmly packed
½ cup granulated sugar 100g
2 large eggs 100g
1 tsp pure vanilla extract 4g
1½ cups all-purpose flour 180g
1 tsp baking soda 6g
1 tsp ground cinnamon 3g
¼ tsp ground nutmeg .5g
¾ tsp kosher salt 2-3g
1½ cups old-fashioned oats 150g, uncooked
1½ cups quick oats 134g, uncooked

For the Cream Filling

¾ cup unsalted butter 170g, (1½ sticks)
2 cups powdered sugar 226g
13 oz. marshmallow fluff 369g (1 jar)
1½ tsp pure vanilla extract 6g
¾ tsp kosher salt 5-6g

Instructions

Preheat oven to 375°F and spray two 8x12-inch baking pans with nonstick spray. Line the pans with parchment so that each edge of the pan has a 2-inch over-flap. Spray the parchment with nonstick cooking spray.
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugars together until creamy. Add eggs and vanilla and beat well.
1¼ cups unsalted butter, ¾ cup dark brown sugar, ½ cup granulated sugar, 2 large eggs, 1 tsp pure vanilla extract
In a medium bowl, whisk the flour, baking soda, cinnamon, nutmeg, and salt together. Add the flour mixture to the wet mixture all-at-once and beat only until flour mixture is incorporated.
1½ cups all-purpose flour, 1 tsp baking soda, 1 tsp ground cinnamon, ¼ tsp ground nutmeg, ¾ tsp kosher salt
Add the oats and mix until incorporated.
1½ cups old-fashioned oats, 1½ cups quick oats
Divide the dough in half and spread half in each pan. Spray a wooden spoon or rubber spatula with cooking spray to prevent the dough from sticking. Work the dough until it reaches across the pans evenly. (If necessary, spray your fingers with cooking spray and spread the dough with your fingers. The dough is somewhat stiff and sticky).
Bake 12-13 minutes, or until the dough is cooked in the middle and is light golden brown. Do not over-bake or the bars will dry out.
While the bars bake, make the cream filling: In the bowl of a stand mixer fitted with the whisk attachment, beat the softened butter until fluffy. Add the powdered sugar and beat until lighter in color and smooth. Add the marshmallow fluff, vanilla, and salt. Beat until light and fluffy. Set aside until ready to use.
¾ cup unsalted butter, 2 cups powdered sugar, 13 oz. marshmallow fluff, 1½ tsp pure vanilla extract, ¾ tsp kosher salt
Transfer the cookie bars to a cooling rack to cool 10 minutes. Lift the bars out of the pans, by the parchment paper and set them back on the cooling rack to completely cool.
When bars are cool, spread the cream filling over one of the uncut 8x12-inch cookies. Remove the parchment paper and place the other 8x12-inch cookie over the cream filling and press gently down. Place the entire large cookie on a larger baking tray and cover it with plastic wrap and foil. The cookies are easy to cut when frozen. Place in the freezer for at least 2 hours or overnight.
Cut the frozen cookie into bars.

Video

Notes

Using an electric mixer ensures everything gets well incorporated.
I find these bars get messy when too warm, so I serve them cold.
Make cookies instead of bars if you prefer a round shape.
Use one 12x16-inch pan, and use 1 cup less dough if you don't have 2 8x12 pans.
Store in an airtight container in the refrigerator for up to 4 days.

Nutrition