These peanut butter M&M cookie bars are my favorite way to bake ahead without losing that soft, fresh-out-of-the-oven texture. They’re thick, chewy, and packed with melty chocolate and crunch.
Table of Contents
Why I Love This Recipe
These cookie bars are the best of both worlds—soft and chewy in the middle with just the right crisp around the edges for that perfect bite. The peanut butter M&Ms bake up beautifully, staying whole so every slice is packed with colorful pops and bursts of peanut buttery goodness.
Add in mini chocolate chips and creamy white chocolate chips, and you get layers of rich flavor without being overly sweet. They’re like M&M cookies, but even easier—and you can’t stop at just one square!
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Key Ingredients and Substitutions
- Butter: Use unsalted, room-temperature butter so it creams smoothly with the sugars. This gives the bars their rich, soft texture.
- Granulated sugar + light brown sugar: The mix of sugars adds depth. Brown sugar gives chewiness while white sugar adds structure and sweetness.
- Eggs: Help bind the dough and keep the bars moist. Use large eggs at room temperature for best results.
- Vanilla extract: Adds a warm, cozy flavor that complements the peanut butter and chocolate.
- All-purpose flour: Gives the bars their sturdy structure while staying soft and tender.
- Baking soda: Provides just enough lift to keep the bars thick without puffing up too much.
- Salt: Enhances all the sweet flavors and balances the richness.
- Peanut butter M&Ms: These add color, crunch, and that iconic peanut butter flavor. You can swap with regular M&Ms or peanut M&Ms if needed.
- Mini chocolate chips: Mix in easily and melt into every bite. Feel free to use regular-sized chips if you prefer.
- White chocolate chips: Add extra sweetness and a creamy contrast to the peanut butter and dark chocolate.
How to Make Peanut Butter M&M Cookie Bars
Preparation
Preheat the oven to 350˚F. Line a 9×13-inch baking pan with parchment paper, leaving some overhang on the sides for easy removal. Measure out all ingredients and let the butter come to room temperature.
Step 1 – Cream the Butter and Sugars
In a large mixing bowl, beat the softened butter, granulated sugar, and light brown sugar together until smooth and creamy. This creates the base for soft, chewy bars.
Step 2 – Add the Eggs and Vanilla
Beat in the eggs one at a time, followed by the vanilla extract. Mix well until the batter is fully combined and smooth.
Step 3 – Combine the Dry Ingredients
In a separate bowl, whisk together the flour, baking soda, and salt. This ensures the leavening is evenly distributed throughout the dough.
Step 4 – Add the Dry Ingredients to the Batter
Gradually add the flour mixture to the wet ingredients, mixing just until combined. Be careful not to overmix to keep the texture soft.
Step 5 – Fold in the M&Ms and Chips
Stir in the peanut butter M&Ms, mini chocolate chips, and white chocolate chips until evenly distributed throughout the dough.
Step 6 – Press Dough Into Pan
Spread the dough evenly into the prepared pan and gently press it down until smooth and level. For an extra pop of color and texture, sprinkle additional M&Ms and chocolate chips on top.
Step 7 – Bake Until Set
Bake for about 40 minutes, or until the top is golden and a toothpick inserted near the center comes out with just a few moist crumbs. Cover loosely with foil about two-thirds of the way through to prevent over-browning.
Step 8 – Cool and Slice
Let the bars cool completely in the pan. Once cool, lift out using the parchment overhang and slice into squares. Store in an airtight container to maintain moisture.
Lynette’s Tip
Cover the bars with foil about two-thirds of the way through baking. This helps them bake through without the tops getting too dark before the center sets.
More Peanut Butter Recipes You’ll Enjoy
Peanut Butter M&M Cookie Bars
Ingredients
- 16 Tablespoons butter room temperature
- 1 cup granulated sugar
- 1 cup light brown sugar
- 3 large eggs large
- 1 1/2 tsp vanilla extract
- 3 cups all-purpose flour
- 3/4 tsp baking soda
- 3/4 tsp salt
- 1 1/2 cups peanut butter M&Ms
- 1 cup mini chocolate chips
- 1/2 cup white chocolate chips
Instructions
- Preheat your oven to 350°F and line a 9×13 baking pan with parchment paper so nothing sticks. In a large bowl, beat together the butter and sugar until the mixture is smooth and well blended. Add in the eggs and vanilla extract, mixing until everything is nicely combined.
- In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add this dry mixture into the butter mixture, stirring until fully incorporated. Fold in the M&Ms and chocolate chips for that pop of color and extra sweetness.
- Spread the batter evenly into your prepared baking pan, patting it down until smooth. Sprinkle a few extra M&Ms and chocolate chips on top for a fun, bakery-style finish.
- Bake for about 40 minutes, or until the bars are cooked through. To keep the tops from getting too brown, cover the pan loosely with foil about two-thirds of the way through baking. Let cool, slice, and enjoy!
Notes
Variations:
- Swap the M&Ms: Try using regular M&Ms, peanut butter chips, or chopped peanut butter cups in place of the peanut butter M&Ms. Each one brings a different texture and flavor.
- Try a Crunchy Addition: Stir in chopped pretzels or roasted peanuts for added crunch throughout the bars.
- Add Different Chips: Mix and match chocolate chips – milk, dark, semi-sweet, or even butterscotch. You can also use all white chocolate chips for a lighter version.
Nutrition
Recipe FAQs
About two-thirds of the way through baking, loosely cover the pan with foil. This helps the center bake through without the top getting too dark.
Yes, regular M&Ms work great too. The peanut butter M&Ms just add an extra flavor layer, but any variety you love will still taste delicious.
Don’t overbake them. Pull them out as soon as the center looks set and a toothpick comes out with a few moist crumbs.
Wait until the bars are completely cool before slicing, and use a sharp knife. Wiping the knife between cuts helps too.
I understand the point of using colored peanut butter M&Ms to make a recipe. But, they’re made by Hershey’s, a company that gets its chocolate from sources that use child slave labor to harvest cocoa beans. (See the Facebook story detailing this.) They’ve pledged to be conflict free by 2020. If they keep their promise, that’s when I plan to buy Hershey’s products again. I,wish you’d do the same. In the mean time, you can get peanut butter chips from a number of sources. If there isn’t a Whole Foods or Trader Joe’s in the nearest town, you can always order them online from Amazon.