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the top of a giant oatmeal cream pie cut into slices

Oatmeal Cream Pie Cookie Bars


  • Author: Jenna Barnard
  • Prep Time: 30 minutes
  • Cook Time: 20 minutes
  • Total Time: 50 minutes + 1 hour cooling
  • Yield: 8-10 bars 1x

Description

These oatmeal cream pie cookie bars are like slicing into a giant oatmeal cream pie. Two layers of soft and chewy oat cookie are sandwiched with sweet buttercream.


Ingredients

Scale

Oat Cookie

  • 1/2 cup (110g) unsalted butter, room temp
  • 1/2 cup (100g) light brown sugar, tightly packed
  • 1/4 cup (50g) granulated sugar
  • 1 large egg, room temp
  • 1 tsp vanilla extract
  • 1/2 cup + 2 tbsp (80g) all purpose flour
  • 1 tbsp cornstarch
  • 1 cup (100g) old fashioned rolled oats
  • 1/2 cup (50g) quick oats
  • 1/2 tsp baking soda
  • 1/2 tsp cinnamon
  • 1/2 tsp salt

Cream Filling

  • 1/2 cup (110g) unsalted butter, room temp
  • 1/2 cup (100g) vegetable shortening
  • 45 cups powdered sugar
  • 23 tbsp milk

Instructions

Oat Cookie

  1. Preheat the oven to 350F and prepare 2 8″ round cake pans*. Coat the inside with a layer of nonstick spray and place a round sheet of parchment paper on the bottom of each pan. 
  2. In a medium bowl, whisk together the flour, cornstarch, oats, baking soda, cinnamon, and salt. Set aside.
  3. In a large bowl using a hand or stand mixer with the paddle attachment, cream together the butter and sugars until light and fluffy (about 2 minutes on medium-high speed).
  4. Add in the egg and vanilla and mix on medium-high speed again for about 2 minutes.
  5. Mix in the dry ingredients in two parts to not overwhelm the batter. Mix JUST until all of the ingredients are combined. Do not over mix.
  6. Split the dough between the two pans and spread it even. 
  7. Bake at for 20-22 minutes or until the edges are a light golden brown.
  8. Place the pans on a cooling rack and allow the cookies to cool for at least 30 minutes, or until the pans are no longer warm to the touch.
  9. Run a knife around the edge of each cookie, turn them out onto your wire cooling rack and place the cookies in the refrigerator to chill firm (about 45 minutes). This will make it easier during the assembly process.

Cream Filling

  1. While the cookies chill, make the buttercream.
  2. In a bowl using a hand or stand mixer with the whisk attachment, mix the butter and shortening until smooth.
  3. Mix in the powdered sugar, one cup at a time. As it begins to thicken, mix in the milk 1 tablespoon at a time in between each cup of powdered sugar.
  4. The buttercream should be fairly thick but easy to spread. Place the buttercream in the refrigerator to chill for about 20 minutes.
  5. To assemble, place one cookie upside-down and peel back the paper. Place the buttercream in a piping bag fitted with a larger round tip, or in a ziplock bag with a corner snipped off. Pipe the buttercream in an even layer on top of the cookie.
  6. Place the other cookie right-side up on top of the buttercream, remembering to peel back the paper beforehand! 
  7. By now, the cookies should be cold but soft enough to slice, and the buttercream should still be cold and thick making these bars easy to slice. I recommend using a serrated knife to saw into the firm curst edges before slicing all the way down into the bars. This stops the buttercream from smooshing out the sides.
  8. Store your oatmeal cream pie bars in the refrigerator but allow to come up to room temp before eating. Enjoy!

Notes

BAKING PANS – You can also use 9 inch pans, just keep an eye on the cookies as they may bake a few minutes faster. If you have them, you can also use 2 8″ square baking pans. And although I haven’t tested it, you can try baking the dough in a single layer in a 9×13″ pan and then cut the cookie in half to sandwich the buttercream in the center.

OATS – If you don’t have both types of oats, you can either use all old fashioned or all quick oats, although I recommend the ratio I have in this recipe. All old fashioned will give you a chunkier texture and all quick oats will give you a more smooth texture.

SHORTENING – You can also use all butter if preferred. Vegetable shortening is used to give it that classic oatmeal cream pie filling texture, just like Little Debbie.

Keywords: oatmeal cream pie, oatmeal cookies, oatmeal cookie bars, oatmeal cream pie cookie bars

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