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This recipe for our delectable, dreamy Reese’s Pieces Oatmeal Cream Pie Bars is perfect for all your fall get-togethers & Halloween parties! Get ready to elevate your baking game and satisfy your cravings with these ultimate oatmeal cream pie bars!

More party treats? You’ll love these spooky Halloween Ghost Brownies, these Reese’s Pieces Magic Bars, these 50 Spooky Fun Halloween Cookies and these Halloween Reese’s Monster Cookie Bars for starters!

Why You’ll Love These Reese’s Pieces Oatmeal Marshmallow Cream Bars

Picture this: a chewy oatmeal cookie base, sandwiched with a fluffy cream filling, and topped with a layer of decadent and creamy marshmallow frosting and delicious Reese’s Pieces Candies. Your mouth watering yet?
These oatmeal cream pie bars are a crowd-pleasing treat perfect for any occasion. We love the peanut butter candies on top!
Moist and delicious! Easy enough to make and taste just like those Little Debbie oatmeal pies only in bar form with a more creamy, gooey frosting that is to die for!
Great cinnamon oatmeal flavor in the bars, as well as soft and chewy with slightly golden crispy edges.

Ingredients for Reese’s Pieces Oatmeal Cream Pie Bars

1 1/4 cups King Arthur Unbleached All-Purpose Flour
1 teaspoon salt
1/2 teaspoon baking soda
12 tablespoons unsalted butter, at room temperature
3/4 cup packed dark brown sugar or light brown sugar – use dark for a richer oatmeal cookie bar
1/3 cup granulated sugar
1 1/2 teaspoons Vietnamese cinnamon, (any cinnamon will do if you don’t have Vietnamese)
1 teaspoon ginger or peanut butter
2 teaspoons King Arthur Pure Vanilla Extract
2 large eggs or 2 flax eggs for vegan option
1 3/4 cups quick-cooking oats or you can pulse old-fashioned rolled oats in a food processor a few times.

Ingredients for Marshmallow Cream Frosting

8 tablespoons unsalted butter, softened
1 cup powdered sugar
7 oz. Marshmallow cream
1 teaspoon King Arthur Pure Vanilla Extract
1/4 teaspoon salt
Toppings: Reese’s Pieces, or anything like chocolate chips, peanut butter chips, chopped nuts, etc.

Instructions How to Make Reese’s Pieces Oatmeal Cream Pie Bars

Preheat the oven to 325°F. Lightly grease an 8-inch square pan and line with parchment paper.
In a medium bowl, whisk together the dry ingredients of flour, salt, and baking soda until well-combined, set aside.
In another large mixing bowl, using a mixer, beat together the softened butter, brown and granulated sugars, cinnamon, ginger, and vanilla until it’s smooth.
Beat in the eggs one at a time, scraping the bowl between additions, so the mixture is thick and creamy.
Stir in the flour mixture just until combined, then add in the quick oats.
Transfer the oatmeal cookie dough to your prepared pan and smooth it into an even layer with an offset spatula.
Bake the oatmeal cream pie bars for 35 to 40 minutes, until the color is a deep golden brown and a toothpick inserted into the center comes out clean. Cool for 10 minutes in the pan on the wire rack, then lift out of pan and let cool completely on the wire rack. Once the bars are cooled, make the frosting!

How to Make Marshmallow Cream Frosting

Beat butter until fluffy.
Mix in the marshmallow fluff, powdered sugar, salt and vanilla and continue mixing on low to medium speed until mixture is light, gooey and creamy. If you want it stiffer, add a little more powdered sugar.
To make it festive, add some Reese’s pieces on top. Cut and enjoy!

Storing Reese’s Pieces Oatmeal Marshmallow Cream Bars

Store your oatmeal cream pie bars in an airtight container at room temperature for up to 3 days.
To make ahead, freeze unfrosted baked bars, then thaw in the refrigerator overnight. Top with marshmallow frosting when ready to serve.

More Variations

If you want to make the marshmallow frosting with crisco instead of butter, feel free to do so. I’m partial to butter, but if you’re wanting these vegan, make sure you’re using vegan butter and vegan marshmallow creme.
You don’t have to add any toppings! Or you can just lightly dust with some cinnamon or add some sprinkles on top for a blast of color.
For some variety ideas, add some mini chocolate chips, dried cranberries, Reese’s peanut butter cups, pecans, walnuts or raisins in your oatmeal cookie base for a delicious twist of flavors.
Love the idea of apples in your oatmeal bars? Add some finely chopped apples for a delicious apple oatmeal bar dessert! Add a delicious cream cheese frosting!
Don’t want frosting? Serve these warm with a scoop of yummy vanilla ice cream and some salted caramel or chocolate fudge sauce on top!
No matter how you serve these, they are amazing with warm, cozy spices! Perfect fall and Halloween oatmeal bar recipe everyone will love!

This Fall and Halloween Oatmeal bar recipe idea is a delicious and satisfying treat that combines the best of both worlds – the classic oatmeal cream pie and the irresistible flavor of Reese’s Pieces. They offer a unique and delectable experience for any dessert lover anytime, anywhere, and any place!

So go ahead and indulge in a batch of these Reese’s Pieces oatmeal cream bar recipe. Share on Pinterest, Instagram and Facebook! Until next time, happy baking!

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