Ever have one of those days when you’re craving something sweet and homemade but don’t feel like dealing with a long list of ingredients? That’s when these cake mix cookie bars come to the rescue! Made with just four ingredients—yes, only four!—these bars are incredibly easy to whip up, and they’re so satisfyingly delicious. The texture is the perfect balance of soft, chewy, and just a little crispy around the edges. Plus, they’re packed with colorful M&M’s, which add a fun touch. Whether you’re making them for a party, a casual get-together, or just a cozy night in, these cookie bars are sure to be a hit.

A sweet childhood memory (and my love for M&M’s)

Growing up, my mom always had a box of cake mix in the pantry, just waiting for those last-minute sweet cravings. I still remember her pulling it out on rainy afternoons, adding a couple of eggs and some butter, and somehow creating the most amazing desserts. My favorite was when she would mix in M&M’s—the little bursts of chocolate were always such a treat. Now, every time I make these cake mix cookie bars, I’m reminded of those cozy afternoons, the smell of something sweet in the oven, and the joy of sneaking a few extra M&M’s before they went into the batter. I love how simple recipes like this can bring back so many happy memories.

A quick look at cake mix cookie bars

These cookie bars are a modern twist on classic cookies, using cake mix as a base. Cake mix desserts started becoming popular in the mid-20th century when convenience foods were on the rise, making baking easier and faster. By adding a few ingredients to a box of cake mix, home bakers could whip up delicious treats without needing a full pantry of baking supplies. The result? Simple, adaptable recipes that taste homemade but require minimal effort. Over time, people began experimenting with cake mix, creating everything from cookies to pancakes to, yes, cookie bars! This recipe is one of those delightful results—a hybrid of cookie and cake that’s easy to make and even easier to enjoy.

Let’s talk ingredients: Cake mix, butter, eggs, and M&M’s

Each ingredient in this recipe serves a specific purpose, so let’s take a closer look.

Yellow cake mix: This is the foundation of the recipe, giving the bars a light, fluffy texture and that classic buttery vanilla flavor. If you’re out of yellow cake mix, you can try a white or chocolate cake mix for a fun twist. Just remember, each flavor will bring its own unique taste.
Butter: Butter adds richness and helps create that soft, chewy texture. I recommend using unsalted butter, but if you only have salted on hand, just reduce the added salt a bit. Melted coconut oil can work as a dairy-free substitute, though it will add a slight coconut flavor.
Eggs: Eggs help bind everything together and add structure to the bars. Make sure your eggs are at room temperature—they’ll mix in better and create a smoother batter.
M&M’s: These add a delightful crunch and a pop of chocolate in every bite. If you want to switch it up, try using mini chocolate chips, Reese’s Pieces, or even chopped nuts. Just be careful not to add too much, or the bars might get too dense.

Kitchen gear: What you need (and what you can skip)

You don’t need much to make these cookie bars, which is part of the beauty of this recipe! Here’s what you’ll want to have on hand:

9×9 baking pan: A square pan is ideal for this recipe because it ensures the bars bake evenly. If you don’t have a 9×9 pan, an 8×8 will work too, but you may need to increase the baking time slightly.
Parchment paper: This makes it so much easier to lift the bars out of the pan once they’re done. Just cut a piece that fits the bottom of the pan and let it hang over the sides for easy lifting.
Mixing bowl and spatula: Since you’re only combining a few ingredients, a medium-sized mixing bowl and a sturdy spatula are all you need. A hand mixer can also work, but isn’t necessary.

Step-by-step: My foolproof method for cake mix cookie bars

Ready to dive in? Let’s make some delicious cookie bars!

Preheat your oven to 350°F: While it’s heating up, prepare your baking pan by spraying it lightly with non-stick spray and lining it with parchment paper. This will make cleanup a breeze, and it’ll help you lift the bars out easily after baking.
Mix the ingredients: In a medium mixing bowl, combine the yellow cake mix, melted butter, and eggs. Stir until everything is well combined and there are no lumps of dry cake mix. The batter will be thick, almost like cookie dough.
Add the M&M’s: Gently fold in the M&M’s, making sure they’re evenly distributed. Be careful not to over-mix, as you don’t want to crush the candies.
Spread into the pan: Transfer the dough into your prepared baking pan. Use a spatula to press it down evenly—it might take a bit of patience since the dough is thick, but just keep at it until it’s spread out in an even layer.
Bake: Pop the pan into your preheated oven and bake for 25-30 minutes. The bars are done when the edges are golden and a toothpick inserted into the center comes out mostly clean.
Cool and cut: Let the bars cool in the pan for about 10 minutes, then use the parchment paper to lift them out. Once they’re cool enough, cut them into nine squares. Now, the only thing left to do is enjoy!

Fun variations to try with your cookie bars

These cake mix cookie bars are so versatile! Here are a few fun twists I’ve tried that turned out great:

Peanut butter chocolate: Use chocolate cake mix instead of yellow and add 1/2 cup of peanut butter chips along with the M&M’s for a rich, Reese’s-inspired flavor.
Gluten-free: If you need a gluten-free option, simply use a gluten-free yellow cake mix. Most major brands offer gluten-free versions, and they work just as well.
Healthier mix-ins: Try adding a handful of chopped nuts, like almonds or pecans, for some extra crunch and protein. You could also add dried fruit, like cranberries or raisins, for a different kind of sweetness.

Serving ideas to make it extra special

For a dessert that really wows, serve these cookie bars slightly warm with a scoop of vanilla ice cream on top. Drizzle a little chocolate or caramel sauce over the ice cream, and you’ve got a dessert that feels restaurant-quality but is made right at home! You can also cut the bars into smaller squares and serve them on a platter for a party or gathering—they’re bite-sized and easy to grab, making them a perfect finger food.

Pairing suggestions

These cookie bars are sweet and rich, so they pair wonderfully with a cold glass of milk (classic, I know). If you’re looking for something different, try them with a vanilla or caramel latte for a cozy vibe. For a refreshing twist, a tall glass of iced coffee or an iced chai latte works beautifully. If you’re serving these bars at a gathering, consider making a big batch of homemade lemonade or even a sparkling fruit punch to complement the sweetness.

Storing and reheating your cookie bars

Store any leftover cookie bars in an airtight container at room temperature for up to three days. If you want them to stay chewy, wrap each bar individually in plastic wrap before storing. You can also freeze these bars for up to a month—just layer them between sheets of parchment paper in a freezer-safe container. To reheat, pop one in the microwave for about 10 seconds to get that warm, fresh-baked feel again.

Scaling the recipe for a crowd

If you’re making these bars for a larger group, simply double the ingredients and use a 9×13 baking pan. The baking time may need a little adjustment—start checking around the 30-minute mark and keep an eye on the color of the edges. When they’re golden and a toothpick comes out mostly clean, they’re ready to go. Just be aware that thicker layers might need a few extra minutes in the oven.

Troubleshooting: What if something goes wrong?

If your bars come out too dry, it could be that they baked a little too long. Next time, check them a few minutes earlier and remember that they’ll continue to firm up as they cool. If they’re too soft and crumbly, try adding an extra tablespoon of butter or a splash of milk to the batter next time for added moisture.

Give these cake mix cookie bars a try!

I hope you’re as excited as I am to try these easy cake mix cookie bars! They’re fun, simple, and so adaptable—you can truly make them your own. Whether you’re baking for a crowd or just satisfying a personal craving, this recipe is a keeper. Let me know how you like them and if you try any fun variations!

FAQ

Q: Can I use a different flavor of cake mix?
A: Absolutely! Chocolate, funfetti, or even spice cake mix can add a fun twist to these bars.

Q: What if I don’t have M&M’s?
A: You can substitute with chocolate chips, chopped chocolate bars, or other candy pieces.

Q: Can I make these dairy-free?
A: Yes! Use a dairy-free cake mix and swap butter for melted coconut oil or vegan butter.

Q: Do I have to use parchment paper?
A: It’s not required, but it makes it much easier to lift the bars out of the pan and clean up.

Q: How long will these bars stay fresh?
A: They’re best enjoyed within three days, but you can freeze them for up to a month for longer storage.