Oreo Sandwich Cookies (Made with Brownie Mix)

These Oreo Sandwich Cookies start with a simple brownie mix and are filled with fluffy Oreo buttercream. Rich, chewy, chocolatey, and packed with cookies-and-cream flavor, they're an easy dessert Oreo lovers will devour.

These Oreo Sandwich Cookies start with a boxed brownie mix but taste like they came straight from a bakery. The cookies bake up rich and chewy with beautiful crackly tops, then get sandwiched together with a fluffy Oreo buttercream filling that's loaded with cookies-and-cream flavor.

I recently took a batch of these to my small group, and they disappeared in record time. One friend couldn't believe they were made with a brownie mix. That's the beauty of this recipe. You get all the flavor and texture of a homemade dessert with a fraction of the work.

Unlike traditional whoopie pies, these sandwich cookies aren't light and cakey. They're chewy, rich, and intensely chocolatey. The contrast between the fudgy brownie cookies and the sweet Oreo filling makes every bite completely irresistible.

There are so many reasons you're going to swoon over this new recipe, friends!

Ingredients

As always, you will find a full, printable recipe card at the bottom of this post, but here's a look at what you'll need. These are simple ingredients you might already have in your pantry or refrigerator.

For the Brownie Cookies

• 1 box brownie mix
• 2 large eggs
• ⅓ cup vegetable oil

For the Oreo Buttercream Filling

• 1 stick (½ cup) unsalted butter, softened
• 2 to 3 cups powdered sugar
• 1 teaspoon vanilla extract
• 2 to 3 tablespoons heavy cream or milk
• 8 to 10 Oreo cookies, finely crushed

How to Make Oreo Sandwich Cookies

These come together so easily and quickly! They're about to become your go-to chocolate cookie!

Step One: Prepare the Cookie Dough

Preheat oven to 350 degrees Fahrenheit.

Line baking sheets with parchment paper.

In a large mixing bowl, combine brownie mix, eggs, and vegetable oil. Stir until a thick dough forms.

Step Two: Bake the Cookies

Using a small cookie scoop, portion dough onto prepared baking sheets, leaving space between cookies for spreading.

Bake for 8 to 10 minutes or until the cookies are set and have developed crackly tops.

Allow cookies to cool on the pan for several minutes before transferring to a wire rack to cool completely.

Step Three: Make the Oreo Buttercream

Beat the softened butter until creamy.

Add powdered sugar, vanilla extract, and enough cream to create a light, fluffy frosting.

Fold in the crushed Oreo cookies and mix until evenly distributed.

Place frosting in a piping bag.

Step Four: Assemble the Sandwich Cookies

Match cookies into pairs of similar size. (This is my favorite part when I make sandwich cookies, finding the perfect duos.)

Pipe or spread Oreo buttercream onto the flat side of one cookie. Top with a second cookie and gently press together.

Serve immediately or refrigerate until ready to serve.

Storage

Store assembled cookies in an airtight container in the refrigerator for up to five days.

For the best texture, allow chilled cookies to sit at room temperature for 15 to 20 minutes before serving.

What to Expect from These Easy Sandwich Cookies

Oh, friends. Every now and again I come up with an idea that works. This is one of those. This cookie works. It really, really works. And can I just say. . .the light, fluffy Oreo buttercream is the absolute perfect complement to the chewy, rich cookies. It adds a lightness, a crisp "bite" and a delicious sweetness.

As I mentioned above, I took these cookies to an event and every single one disappeared. In fact, I was kind of shocked at how quickly they got scooped up.

I can't wait to make these again. Now that I know the recipe works so beautifully, nothing's holding me back!

Variations

This was a perfect recipe but you know me. . .I always love to change things up. Here are some ideas for next time:

Golden Oreo Sandwich Cookies

Swap regular Oreos for Golden Oreos in the filling for a vanilla cookies-and-cream version.

Mint Oreo Version

Use Mint Oreos to create a chocolate-mint sandwich cookie.

Extra Chocolate

Add a tablespoon of cocoa powder to the buttercream for an even richer chocolate flavor.

Party Tray Presentation

Roll the exposed edges of the filling in additional crushed Oreos for a bakery-style finish.

Frequently Asked Questions

Are these whoopie pies?

No. Traditional whoopie pies are soft and cake-like. These cookies have a chewy brownie texture with a creamy filling.

Can I use homemade brownie batter?

This recipe was developed using a boxed brownie mix. Homemade brownie batters vary widely and may produce different results.

Can I freeze these cookies?

Yes. Store assembled cookies in an airtight freezer-safe container for up to two months.

Do I have to use Oreos?

No. Any chocolate sandwich cookie will work, but Oreos provide the classic cookies-and-cream flavor.

Why are my cookies crackly on top?

That's one of the best features of brownie cookies! The shiny, crackly tops are a sign that the cookies baked properly and developed their signature texture.

Final Thoughts

These Oreo Sandwich Cookies prove that a simple brownie mix can become something truly special. Rich chocolate brownie cookies paired with fluffy Oreo buttercream create a dessert that's chewy, decadent, and packed with cookies-and-cream flavor.

Whether you're making them for a party, a cookie exchange, or simply because you're craving chocolate, don't expect leftovers. They disappear fast.

Thanks for stopping by! If you make these yummy sandwich cookies and love them, please leave a comment or review.

Before you go, why not pin some photos to your Pinterest boards?

Janice Thompson is a professional baker, cake designer, and author with over 20 years of experience creating unique cakes and desserts. She’s the creator of Out of the Box Baking, where she shares her favorite doctored cake mix recipes, tutorials, and baking tips. Learn more →