Cake Batter Monster Cookie Sandwiches

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Funfetti meets oatmeal cookies! These Cake Batter Monster Cookie Sandwiches are chewy oatmeal cookies made with vanilla cake mix and loaded with MnMs, chocolate chips and sprinkles. Finish them off with some vanilla buttercream for the perfect cookie sandwich.

Stacked oatmeal cookie sandwiches

Cake Batter Monster Cookies

These Cake Batter Monster Cookie Sandwiches are so fun! It’s my favorite oatmeal cookies but made with cake mix, sprinkles, MnMs and white chocolate chips. They’re chunky and down right delicious. 

Over the years, I’ve perfected my oatmeal cookies. Equal parts granulated and brown sugar makes them soft & chewy. With the addition of cake mix, these are extra soft and tender. 

Since I like to go a little overboard with my desserts, I chose to make these cookie sandwiches. This is totally optional, but let’s face the facts, you’re going to eat more than one cookie, so why not smoother some vanilla buttercream in between. 

Go ahead and take a nice big bite and let that buttercream smoosh out of the sides, extra napkins are required. 

A monster cookie leaning up against a milk glass

It’s all in the cake mix

You’ll notice this recipe calls for 1/4 cup of cake mix. That’s dry cake mix, right from the box. You can use a vanilla, yellow or white cake mix but I think the vanilla or yellow have better flavor. 

The cake mix helps make these really tender but also it’s where the flavor comes from. After all, these are cake batter oatmeal cookies! 

HOW TO MAKE MONSTER COOKIES

  • Soften the cold butter in the microwave is for 10-12 second
  • Cream the butter & sugars until fluffy 
  • Add the egg and vanilla 
  • Combine and add the dry ingredients 
  • Add the MnM, chocolate chips & sprinkles
  • Bake for 13-15 minutes. You will pull them out of the oven before the centers are fully baked through. Leave them on your baking sheet for several minutes.

These cookies shape the best when they’re full of MnMs and chocolate chips, so if you find the bottom of your mixing bowl is really doughy, go ahead and throw some more of the good stuff in there! 

A stack of three cookie sandwiches with vanilla buttercream, the one on top had a bite taken out of it

3 tips for perfect cookies

  • Line your baking sheets with silicone baking mats. These are game changers for cookie baking. It helps the cookies from spreading and burning on the bottom or edges.
  • To ensure your cookies bake evenly, use a cookie scoop to keep the cookies are the same size.
  • Right when you pull them out of the oven, take an angled spatula, a cookie spatula and any flat surface and push the edges of the cookies back towards the center of the cookie. This makes a nice round shape and also helps keep the center nice and puffy. It also works with a round cookie cutter. 

an overhead shot of MnM oatmeal cookies

How to frost these cookies

It’s best to let the cookies cool completely before adding the frosting, or you might have quite the mess on your hands.

I like to use a piping bag or ziplock bag to swirl my frosting and I love a french star tip because it gives the frosting a little bit of texture around the outside edge. 

  • Find two cookies that are the similar in size. 
  • Fill your piping bag and then cut off the tip of the bag.
  • Swirl the frosting on one side of the cookie.
  • Place a second cookie on top and gently press down. 
  • Then you can roll the edges in more sprinkles

vanilla buttercream swirled on an oatmeal cookie

CAN I FREEZE THESE COOKIES? 

Yes, these freeze nicely. I prefer to place them in an airtight container and I recommend freezing them without the frosting. Thaw completely before adding the frosting. 

HOW DO I KEEP THESE COOKIES FRESH?

Store them in an airtight container or in a Ziploc bag whether they’re frosted or not. 

A giant stack of MnM oatmeal cookies

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These Cake Batter Monster Cookie Sandwiches were originally published in 2016 and updated in 2020

 

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Stacked oatmeal cookie sandwiches

Cake Batter Monster Cookie Sandwiches

  • Prep Time: 15 minutes
  • Cook Time: 14 minutes
  • Total Time: 29 minutes
  • Yield: 8 sandwiches - 16 cookies

Description

Cake Batter Monster Cookies are chewy oatmeal cookies with vanilla cake mix and a layer of creamy vanilla frosting. The cookies are filled with MnMs, sprinkles and white chocolate chips.

Ingredients

  • 1/2 cup (113g) unsalted butter, cold
  • 1/2 cup (95g) granulated sugar
  • 1/2 cup (110g) light brown sugar
  • 1 large egg
  • 1 tablespoon (15ml) pure vanilla extract
  • 1 cup (140g) all purpose flour
  • 1/4 cup (35g) vanilla cake mix, dry
  • 1 cup (80g) rolled oats
  • 1/2 teaspoon baking soda
  • 1/2 teaspoon salt
  • 1/2 cup (90g) white chocolate chips
  • 1/2 cup MnMs
  • 1/4 cup sprinkles

For the frosting

  • 3/4 cup (170g) unsalted butter, cold
  • 2 1/2 cups (325g) powdered sugar
  • 2 teaspoons (10ml) pure vanilla extract
  • 1 tablespoon (15ml) milk or heavy cream
  • Additional Sprinkles for garnish

Instructions

  1. Preheat the oven to 350° F. Soften the cold butter in the microwave for 10-15 seconds. Combine the softened butter with the brown and granulated sugar. Beat on medium speed until well combined, 2-3 minutes.
  2. Next add the egg and vanilla extract and continue beating until well incorporated.
  3. In a separate bowl, combine the dry ingredients: flour, cake mix, oats, salt and baking soda. Stir to combine and slowly add the dry ingredients into the dough, mixing on low speed until dough starts to form.
  4. Before the dough thickens, add the chocolate chips, MnMs and sprinkles. Beat a couple of times until they start to incorporate.
  5. Line a baking sheet with parchment paper or a silicone baking sheet. Scoop the dough using a large cookie scoop and place on a sheet pan, 2 inches apart.
  6. Bake for 13-15 minutes. The center of the cookie should be slightly under baked but not too gooey. Allow to cool on the baking sheet for 5-10 minutes before transferring to a wire rack to cool.
  7. For the frosting: Cut the butter into smaller pieces. Using the paddle attachment, whip the butter for 5-7 minutes, scraping down the bowl occasionally, beating until the butter is very fluffy.
  8. Add the powdered sugar, vanilla extract & heavy cream. Ensure the powdered sugar is well combined, then and whip for 3-4 minutes at high speed.
  9. To assemble the cookies, find two cookies that are similar in size. Use a piping bag or Ziploc bag and cut of the tip off the bag, swirl the frosting on one side of the cookie. Place a second cookie on top and gently press down. Then you can roll the edges in additional sprinkles.

Notes

  • Cake mix: Vanilla, yellow or white cake mix will work.
  • Oats: I prefer to use rolled oats but quick oats will also work
  • Storage: Keep these stored in an airtight container or Ziploc bag
  • When your cookies come out of the oven and they do spread or are misshaped, take a flat edge, such as a knife and press the edges of the cookie back towards the middle of the cookie, shaping it into a circle.
  • This recipe can easily be doubled. As written it makes 16 cookies (or 8 cookie sandwiches)
Nutrition Information:
1 Cookie Sandwich
743
78g
36g
99g
1g
5g
104mg
  • Category: Cookies
  • Method: Baked
  • Cuisine: American

Keywords: oatmeal cookies, monster cookies, MnM cookies

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27 Responses
  1. Robin Smalley

    I have looked all over for the bday cake mms (even crossing the border to the states!) and have had no luck!
    What would you substitute them with?
    Thanks

  2. Sarah

    These look divine and I plan to make them for a Labor Day Weekend BBQ…but I have a potentially stupid question: are there oats in these cookies? Because the description mentions oatmeal cookies, but I do not see oats in the ingredient list. I want to make sure I’m not doing something wrong… Thank you!!!

    1. Beyond Frosting

      Oh my word! Thank you Sarah! Yes, there are quick oats in this recipe and it appears they were missing from the recipe. Thank you for letting me know!

  3. Tammy

    These look great and perfect for a school birthday treat! I am curious though… how necessary is the butter extract? Does it make a huge difference in flavor? Thanks for sharing!

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