Peanut Butter Cookie Bars With M&Ms

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Soft and chewy cookie bars bursting with peanut butter goodness, M&M’s and chocolate chips. This recipe is easy, delicious, and the perfect treat for any occasion!

These M&M Cookie Bars have stolen my heart.

I might say a lot of romantic things about cookies, but these bars are truly something special.

These bars are so chewy and soft, very peanut buttery, and they look super colorful with all those cute little M&M’s stippled throughout.

What you’ll love most about these bars is that the dough is super easy to make and doesn’t need to be chilled prior to baking.

M,eaning you can whip up a batch in a flash! And it’s a good thing too– because these cookie bars are literally perfect for any occasion that calls for a delicious dessert.

On top of that, these bars yield quite a few, so they’re perfect for a crowd!

Let’s go make a pan right now!

Ingredients For This Peanut Butter Cookie Bar Recipe

• Unsalted butter– I like my butter softened but still cool, meaning you can pick up the stick with your fingers easily, but it’s not rock hard. I like this temp for butter to make a dense and fudgy bar.
• Smooth peanut butter – you can use crunchy if you prefer! I just use standard commercial creamy peanut butter.
• Brown sugar (dark or light)– either work, but when you’re measuring, pack the brown sugar firm in the measuring cup and then level it off.
• Granulated sugar– the combination of brown sugar and white sugar keeps these cookie bars sweet, and helps them not be too dense (or bake forever in the oven)
• Large egg and an additional egg yolk – this combo will keep the bars fudgy and chewy.
• Vanilla extract
• All-purpose flour– spoon and level your flour into the measuring cup when measuring. Too much flour will make these bars heavy and dry.
• Baking powder + Baking soda
• Coarse Kosher Salt – if you have table salt, or a fine sea salt, cut the amount called for in the recipe by half.
• M&M Candies – I use standard M&Ms, but if you’re making these for a holiday, use the fun colored ones!
• Semisweet chocolate chips– the extra bits of semisweet chocolate are a must for these peanut butter cookie bars. They’re nice to bite in to and they help offset the sweet candy shell of the M&Ms.

How To Make M&M Cookie Bars

Preheat the oven to 350°.

Line a 13 X 9 pan with two pieces of aluminum foil, crisscrossed in the center, and with a little overhang on the sides. Spray the foil lined pan with cooking spray (or grease with butter) and set aside.

With a mixer (stand or hand) beat the butter until smooth.

Add peanut butter and beat until fluffy.

Next, add the sugars and beat the mixture until it’s well incorporated and slightly lighter in color. Scrape down the sides of the bowl with a rubber spatula.

Add the whole egg, egg yolk, and vanilla and mix until just blended.  

With the mixer on low, add the flour, baking soda, baking powder, and salt. Mix until the flour is almost fully incorporated in the dough–there should still be visible streaks of flour showing.

Add the M&M’s and chocolate chips and gently fold by hand until fully incorporated. Do not overmix.

Press cookie dough into the prepared 13 x 9 baking dish.

Bake at 350° for 22 min, until the edges are lightly browned and puffed and the center is just set.

Let the bars cool completely at room temperature.

Once cooled, gently lift bars from the pan using the foil overhangs and set onto a cutting board.

Carefully remove the foil from the bars, and trim the edges if desired.

Cut into 24 neat squares and enjoy!

Pro Tips

Here are a couple of tips to make sure your M&M cookie bars come out super soft and chewy every time:

1. Don’t over mix the dough! We barely mix the flour in fully before adding the M&M’s and chcocolate chips. The reason being that when we stir in the chocolate, that’s when we want to finish mixing the dough. We don’t want to fully mix the dough and then add the candy. The bars at that point would be overworked and tough.
2. Fold in the chocolate chips and M&M’s. By doing this last step by hand, we make sure the candy and chocolate stay intact and that we don’t overmix the dough.
3. Slightly underbake the cookies. By underbaking the bars (just barely set to the touch), we ensure they stay soft and chewy. By underbaking a little, we also account for any carryover cooking that may occur while the cookie bars are sitting in the pan cooling.

Storing Your Peanut Butter Cookie Bars

Store these bars in an airtight container at room temperature for up to a week.

These bars can also be kept in the fridge to extend their shelf life. Just keep them in an airtight container or wrap them really well in plastic wrap.

Can I Freeze These Bars?

You sure can! They freeze beautifully!

As a matter of fact, I love freezing these bars–especially since this recipe makes a lot.

When I’m ready to devour these bars, I let them thaw in the fridge just until they’re soft enough to bite into. Once they’ve softened, I just eat them cold from the fridge.

As often as I can.

You can also enjoy previously frozen bars at room temp. Just let them thaw completely in the fridge before moving them to the counter to warm up.

Variations and Customizations

This is the fun part! There are so many ways you can tweak the candy or chocolate to totally customize these bars to fit any occasion!

• Change up the colors of the M&M’s to fit the holidays (orange and black for Halloween bars; red and green for Christmas; pink, white and red for Valentine’s Day!)
• Use peanut M&Ms or peanut butter filled M&Ms to make the ultimate peanut butter cookie bars.
• Trade the chocolate chips for peanut butter chips

Some Other Sweet Treats You May Enjoy:

• Golden Grahams S’mores Bars
• Perfect Cheesecake Squares
• Chocolate Covered Popcorn
• From Scratch Birthday Cake Cookies
• Frosted Sugar Cookie Bars

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