M&M Cookie Bars

These M&M cookie bars prove that there are two kinds of people in this world: Those who bake cookies one spoonful at a time and those who understand the glory of pressing the whole thing into a pan and calling it a day. I am firmly in the second camp and, let’s be honest, an unapologetic M&M’s obsessive. These bars have everything I love about a classic cookie recipe—chewy edges, a gooey center and a buttery flavor—but without the fuss of scooping and waiting for trays of individual cookies to bake.

When they come out of the oven, warm and golden, the M&M’s glisten like edible confetti. M&M cookie bars will be your next go-to for movie nights, bake sales and any day that needs a little color therapy. They disappear fast, smell like happiness and look as if you spent all day baking.

M&M Cookie Bar Ingredients

• Butter: Use unsalted butter so you can control the salt level. Make sure it’s softened (not melted!) before you start—cold butter won’t cream properly and melted butter will make the bars greasy. If you’re shopping, grab real butter, not margarine—the flavor difference is everything.
• Sugar: Plain granulated sugar gives the bars that crisp edge and helps balance the brown sugar’s richness.
• Brown sugar: Packed light brown sugar adds chew and a subtle caramel flavor. If you have only dark brown sugar, you can use it—it’ll make the bars slightly richer and more molasses-forward.
• Vanilla extract: Real vanilla extract gives these bars a warm bakery-style depth. Choose one of these favorite brands of vanilla for the best results.
• Eggs: Use room-temperature eggs for baking; cold eggs can make your batter seize or separate.
• All-purpose flour: Stick with a classic all-purpose flour for the best structure. Measure flour carefully using the spoon-and-level method (don’t scoop directly from the bag; it packs too tightly).
• Baking powder: This leavener gives the bars a little lift without making them cakelike.
• Salt: Regular table salt works perfectly, but if you have flaky sea salt, you can sprinkle a pinch over the top for extra flair and flavor.
• White baking chips: White baking chips add creamy sweetness and contrast to the chocolate M&M’s. Ghirardelli or Guittard are two of the best brands if you want a high-quality finish, but store brands work great too.
• M&M’s: The star of the show! Regular M&M’s hold their shape best, but you can experiment with different flavors (like peanut butter, hint hint), minis, or seasonal varieties for color and crunch.

Directions

Step 1: Start the dough

Preheat the oven to 350°F. In a large bowl, cream together the butter, granulated sugar, brown sugar and vanilla until the mixture is light and fluffy, five to seven minutes.

Editor’s Tip: There are several ways to soften butter quickly, including shredding it or placing it under a warm glass for a few minutes.

Beat in the eggs, one at a time.

Step 2: Add the dry ingredients and mix-ins

In a separate bowl, whisk together the flour, baking powder and salt. Then, gradually add the dry ingredients to the creamed mixture.

Stir in the white baking chips and 1 cup of M&M’s.

Step 3: Bake to golden perfection

Spread the batter evenly into a greased 13×9-inch baking pan.

Sprinkle the remaining 3/4 cup of M&M’s over the top. Bake for 25 to 30 minutes or until golden brown and a toothpick inserted near the center comes out with moist crumbs. Cool completely on a wire rack before cutting into bars.

Editor’s Tip: Start checking your bars at 25 minutes—the difference between chewy and dry happens fast!

M&M Cookie Bar Variations

• Add some caramel: Add caramel bits or chopped soft caramels for a gooey, rich twist. Drizzle a little caramel sauce on top with a pinch of salt for a real big finish.
• Go nuts: Fold in walnuts or pecans for a bit of texture and nutty depth.
• Change the chips: Use dark or milk chocolate chips instead of white baking chips. Peanut butter chips are also a delicious choice. Get creative with a variety of different flavored chips.

How to Store M&M Cookie Bars

Store your M&M cookie bars in an airtight container at room temperature. They’ll stay soft and delicious for several days—perfect for lunchboxes, road trips or an “I deserve a cookie” moment.

How long do M&M cookie bars last?

M&M cookie bars last up to five days when stored in an airtight container at room temperature. If they start to dry out, one cookie storage trick is to tuck a slice of bread in the container to keep them soft.

Can you freeze M&M cookie bars?

Yes! M&M cookie bars freeze beautifully. Cut them into squares, wrap each individually in storage wrap, and then store them in a freezer-safe bag or container. They’ll keep for up to three months. Thaw at room temperature before serving, or microwave for a few seconds to soften.

M&M Cookie Bar Tips

How do you ensure M&M cookie bars remain chewy?

To keep M&M cookie bars chewy, start checking them about five minutes before the recommended baking time—they should be just set with moist crumbs, not dry. Also, use the right-sized baking pan; a pan that is too large can cause the bars to be thin and crisp instead of thick and soft.