Fudgy M&M Cookie Bars

I baked these cookie bars, I wasn’t actually planning on it. I had promised a batch of chocolate chip cookies for a small gathering, but halfway through, I realized I was out of patience for scooping dough onto trays. Instead, I pressed everything into a pan, sprinkled on a generous layer of M&M’s, and hoped for the best.

When I pulled the pan from the oven, the edges were perfectly golden, the center had that glossy, just barely set look, and the smell filled the kitchen like a cozy hug. Once cooled and sliced, each square revealed gooey chocolate chips and colorful pops of candy shining through like little stained glass windows.

These bars became the unexpected star of the table. Guests who reached for just one kept sneaking back for more, and the pan was empty long before the evening ended.

Short Description

Fudgy M&M Cookie Bars are soft, chewy, and loaded with chocolate chips and colorful candies. Easy to make in one pan, they’re perfect for parties, bake sales, or a fun treat at home.

Key Ingredients

• 1 cup (2 sticks) unsalted butter, softened
• 1 cup packed light brown sugar
• ½ cup granulated sugar
• 2 large eggs, at room temperature
• 1 tablespoon pure vanilla extract
• 2 ¾ cups all purpose flour
• 1 teaspoon cornstarch
• 1 teaspoon baking soda
• ½ teaspoon fine sea salt
• 1 ½ cups milk chocolate M&M’s candies, divided
• 1 cup semi sweet chocolate chips

Tools Needed

• 9×13 inch metal baking pan
• Parchment paper
• Stand mixer or hand mixer
• Mixing bowls
• Measuring cups and spoons
• Rubber spatula
• Wire cooling rack

Cooking Instructions

Step 1: Prep and Preheat
Preheat your oven to 350°F (175°C). Grease a 9×13 inch metal baking pan and line it with parchment paper, leaving an overhang on two sides so you can lift the bars out later.

Step 2: Cream Wet Ingredients
In a stand mixer fitted with the paddle attachment, beat the softened butter, brown sugar, and granulated sugar together on medium speed for 2–3 minutes.

Step 3: Incorporate Eggs and Vanilla
Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract until combined.

Step 4: Combine Dry Ingredients
In a separate bowl, whisk together the flour, cornstarch, baking soda, and salt.

Step 5: Form the Dough
Use a spatula to fold in 1 cup of the M&M’s and all of the chocolate chips until evenly distributed.

Step 6: Press and Top
Scatter the remaining ½ cup of M&M’s over the top and press them lightly into the surface.

Step 7: Bake
Bake for 22–26 minutes, until the edges are golden brown and firm. The center should look slightly soft this is what gives the bars their fudgy texture.

Step 8: Cool and Slice
Cool the bars completely in the pan on a wire rack. Lift them out using the parchment paper and transfer to a cutting board.

Why You’ll Love This Recipe

Soft and chewy texture with a fudgy center

Easy one pan method, no scooping required

Perfect balance of chocolate chips and candy crunch

Great for sharing at parties or gifting

Kid friendly, colorful, and fun

Mistakes to Avoid & Solutions

Mistake 1: Overbaking
The bars can dry out quickly if left in the oven too long.
Solution: Pull them out when the center still looks slightly soft. They’ll continue setting as they cool.

Mistake 2: Using cold butter
Cold butter won’t cream properly with sugar, leading to dense bars.
Solution: Let your butter soften at room temperature for at least 30 minutes before starting.

Mistake 3: Skipping parchment paper
Without it, bars may stick to the pan or break apart when removed.
Solution: Always line with parchment and leave an overhang for easy lifting.

Mistake 4: Not measuring flour correctly
Too much flour leads to dry, cakey bars.
Solution: Spoon flour into your measuring cup and level it off, rather than scooping directly from the bag.

Mistake 5: Adding all M&M’s into the dough
They’ll sink and disappear inside.
Solution: Reserve half for sprinkling on top so the bars stay colorful and eye catching.

Serving and Pairing Suggestions

Cut into small squares for a party platter

Serve warm with a scoop of vanilla ice cream

Pack into lunchboxes as a fun treat

Pair with a glass of cold milk for a classic combo

Wrap individually in parchment for bake sale portions

Storage and Reheating Tips

Store bars in an airtight container at room temperature for up to 5 days

Refrigerate for up to 1 week if you prefer them firmer

Freeze in layers with parchment between bars for up to 2 months

Reheat in the microwave for 10–15 seconds for that just baked warmth

FAQs

1. Can I use peanut butter M&M’s instead of milk chocolate?
Yes, peanut butter M&M’s add a nutty twist. Just keep the same measurement.

2. How do I know when the bars are done if the center looks soft?
Look for golden brown edges and a slightly glossy center. They’ll firm up as they cool.

3. Can I double the recipe?
Yes, use two 9×13 pans or one larger sheet pan, adjusting baking time as needed.

4. What if I don’t have cornstarch?
You can skip it, but cornstarch helps keep the bars soft and tender.

5. Can I reduce the sugar?
You can cut ¼ cup from the granulated sugar, but reducing too much may affect texture.

Tips & Tricks

Chill the dough for 15 minutes before baking if your kitchen is warm.

Press extra chocolate chips on top for more gooey pools of chocolate.

Slice with a sharp knife dipped in hot water for clean edges.

Swap the M&M colors to match holidays or party themes.

Recipe Variations

Peanut Butter Swirl Bars: Add ½ cup creamy peanut butter to the wet ingredients, reducing butter to ¾ cup. Swirl extra peanut butter on top before baking.

Festive Holiday Bars: Use red and green M&M’s for Christmas, pastel for Easter, or orange and black for Halloween.

Nutty Crunch Bars: Stir in ½ cup chopped walnuts or pecans along with the chocolate chips.

Caramel Drizzle Bars: After cooling, drizzle with melted caramel and a sprinkle of flaky sea salt for a sweet salty upgrade.

White Chocolate Twist: Swap half of the semi sweet chocolate chips for white chocolate chips for a creamier sweetness.

Final Thoughts

Fudgy M&M Cookie Bars are the kind of bake that wins hearts instantly. They’re festive enough for parties but simple enough for everyday cravings. I like how they balance chewy edges with soft, fudgy centers, all while delivering bursts of chocolate in every bite.

The colorful candies make them irresistible to kids, yet the richness of brown sugar and chocolate chips keeps adults reaching for seconds. Every slice feels like a little celebration in itself, and once you bake them, you’ll want to share them with everyone around you.