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Oatmeal Whoopie Pies

Soft oatmeal cookies hold a generous amount of marshmallow buttercream. These are sweet, nostaglic, and delicious.

If you like oatmeal cookies, you’ll love these whoopie pies. Enormous, soft cake-like cookies filled with the most amazing marshmallow filling.

plate of 3 finished whoopie pies.

❤️ Why you’ll love this recipe

  • More fun than cookies or cake. There’s something about a huge cookie sandwich that makes people smile.
  • The filling! Buttercream meets marshmallow creme. Yum.
  • They’re easy to make. You’re just making cookies and icing, really.

This is an overview of the ingredients. You’ll find the full measurements and instructions in the printable recipe at the bottom of the page.

ingredients on concrete counter.

Here’s what you’ll need to make these old-fashioned treats:

  • unsalted butter 
  • brown sugar
  • granulated sugar
  • eggs
  • vanilla extract
  • all-purpose flour
  • cinnamon
  • baking soda
  • baking powder
  • salt
  • quick oats 
  • old-fashioned oats
  • powdered sugar
  • marshmallow cream

🍴Instructions

Step One

cookie batter before and after adding oats.

Beat the butter and sugar in a stand mixer on medium speed until light and fluffy, or about 5 minutes. Beat in the egg and vanilla. Then scrape down the side of the bowl. Combine the flour, salt, baking powder, and baking soda in a large bowl. Reduce the mixer speed to low. Add 1/2 cup of the dry ingredients to the butter mixture at a time, alternating with milk. Stir in both types of oats by hand or on the lowest mixer speed.

Step Two

cookie dough before and after baking.

Measure out 3-4 tablespoons of batter for each cake. You will be able to make 6 cakes per sheet. Put the baking sheets in the oven and bake at 350 degrees for 15-18 minutes. When both sheets are done, a cake tester will come out clean, but the cakes will be soft. Let the cakes cool completely on a cooling rack.

Step three

whipped marshmallow filling.

Use a mixer on medium speed to beat the powdered sugar and butter together until they are light and fluffy. Add the salt and vanilla. Add the marshmallow cream and beat until it is fully combined.

Step Four

cooling rack with cookies adding filling.

Spread 1/4 cup of filling on the flat side of half of the cakes. Put the other cakes on top to make a sandwich. Serve right away or store in the fridge.

🥫 Storage instructions

These will keep just fine at room temperature for a day or two as long as your kitchen is cool. In a warm, kitchen, the filling might get too soft. In that case, just pop them in the fridge.

You can freeze leftovers, but layer them in between layers of wax paper so they don’t stick together in the freezer. I usually just let them defrost on the counter for 20 minutes and eat them partially frozen.

🔍 FAQs

Do I really need both kinds of oats?

Umm…. you could use just one kind. But I prefer the blend.


What can I use instead of marshmallow fluff?

Just use your favorite buttercream recipe. It will be a slightly different flavor, but just as delicious.

Can I add raisins or nuts to the batter?

You could. I tried it once with raisins and thought it was weird. But you might like it.

👩🏻‍🍳 Expert tips

  • Use a 1/4 cup cookie scoop for perfectly even cakes.
  • Be sure to let the cakes cool completely before spreading on the filling.

📘 Related Recipes

🍽 Serve it with

These are perfect when you need something that kids and adults will both love. The following recipes are too:

hand holding whoopie pie.

📖 Here’s the recipe

close up view of oatmeal whoopie pies.
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Oatmeal Whoopie Pies

Print Recipe
Soft oatmeal cookies hold a generous amount of marshmallow buttercream. These are sweet, nostaglic, and delicious.
Prep Time:30 mins
Cook Time:20 mins
Total Time:50 mins
Click here to grab a free seasonal e-cookbook!

Equipment

Ingredients

Cookies

  • 1 cup unsalted butter softened
  • 1 cup brown sugar packed
  • 1 cup granulated sugar
  • 2 eggs
  • 2 teaspoons vanilla extract
  • 2 cups all-purpose flour
  • teaspoons cinnamon
  • 1 teaspoon baking soda
  • 1 teaspoon baking powder
  • 1 teaspoon salt
  • ½ cup milk whole preferred, but 2% is okay
  • quick oats not instant
  • old-fashioned oats

Marshmallow Filling

  • 12 tablespoons unsalted butter softened
  • 1 cup powdered sugar
  • 1 teaspoon vanilla
  • ¼ teaspoon salt
  • 2 cups marshmallow cream uch as Marshmallow fluff brand

Instructions

Make the Cakes

  • Preheat the oven to 350 degrees with two racks, in the upper middle and lower middle positions. Line 4 baking sheets with parchment paper.
  • Beat the butter and sugar in a stand mixer on medium speed until light and fluffy, or about 5 minutes. Beat in the egg and vanilla and scrape down the side of the bowl.
  • Combine the flour, salt, baking powder, and baking soda bowl in a large bowl. Reduce the mixer speed to low. Add the dry ingredients to the butter mixture 1/2 cup at a time, alternating with the milk, beginning and ending with the flour. Stir in both types of oats by hand or on the lowest mixer speed.
  • Scoop 3-4 tablespoons of batter onto baking sheets. (Measure out the first one and then eyeball the rest.) You will be able to fit 6 cakes per baking sheet. There should now be 16-24 cakes. Bake at 350 degrees for 15-18 minutes, switching the baking sheets halfway through. Bake the second batch. When fully baked, a cake tester will come out clean, but the cakes will still be soft. Remove to a cooling rack and allow to cool completely.

Make the Filling

  • Beat the powdered sugar and butter together until light and fluffy using a stand mixer on medium speed. Add the salt and vanilla. Add the marshmallow cream and beat until fully combined.

Assemble

  • Spread 1/4 cup of filling onto the flat side of half of the cakes. Place the remaining cakes on top to make a sandwich. Serve immediately or refrigerate.

Notes

If the filling seems too soft and is not staying on the cakes, refrigerate them until it firms up.
 
Course: Dessert
Cuisine: American, Southern
Keyword: oatmeal cream pies, oatmeal whoopie piess, whoopie pie recipes
Servings: 12 servings
Author: Katie Shaw
Did you make this recipe?Tag me @heartscontentfarmhouse so I can see!

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