This year I wanted a dessert that felt like a cozy kitchen hug: familiar, colorful, and simple enough to make while the tree lights blink in the background. These Christmas M&M cookie bars exactly fit the bill. I first developed the formula during a busy holiday baking marathon when my oven space was limited and I needed something festive that could be made in a single pan. The result was a golden, chewy slab that slices into tidy bars—crispy on the edges, chewy in the middle, and dotted with glossy holiday candies and pockets of chocolate.

What makes these bars special is their texture balance and ease. Instead of fussing with scooping dozens of round cookies, you get even pieces every time and less hands-on work. The brown sugar anchors the chewiness, butter gives the rich mouthfeel, and a generous scattering of red, green, and white M&Ms adds color and a little crunch in each bite. They became an instant favorite among neighbors at our annual cookie exchange—people loved how the candies held their shape and the bars stayed soft for days when stored properly.

Ingredients

• Unsalted butter (1 cup): Use good-quality European-style butter if you want extra richness; soften at room temperature so it creams smoothly. Salted butter works in a pinch—reduce added salt slightly.
• Granulated sugar (1 cup): Provides lift and helps with crisping at the edges. I prefer standard white cane sugar; it melts cleanly into the batter.
• Brown sugar, packed (1 cup): Adds moisture, molasses flavor, and chew—light or dark both work, but dark adds more caramel depth.
• Eggs (2 large): Room temperature eggs incorporate more evenly—take them out 20 minutes before starting for best results.
• Vanilla extract (2 teaspoons): Pure vanilla gives depth. I keep a small bottle of good-quality vanilla for baking—artificial vanilla will still work.
• All-purpose flour (2 ¾ cups): Spoon into the measuring cup and level it off for accuracy. Too much flour will dry the bars; too little makes them spread excessively.
• Baking soda (1 teaspoon): Provides a modest lift and helps the crumb set—ensure it’s fresh for best rise.
• Salt (½ teaspoon): Balances sweetness and enhances flavor—use fine salt so it disperses evenly.
• Chocolate chips (1 cup): Semi-sweet chips are classic; milk chocolate works for sweeter bars, dark for more contrast.
• Holiday M&Ms (1–1½ cups): Red, green, and white candies—use 1 cup for lighter color, 1½ cups for more candy per bite. Reserve a few to press on top.
• Optional extra candies: Press a few whole M&Ms on top before baking for a festive finish and better color after slicing.

Instructions

Preheat and prepare the pan: Preheat the oven to 350°F. Line a 9x13-inch baking pan with parchment paper, leaving an overhang to lift the bars easily. Lightly grease the parchment to ensure a clean release. The parchment method prevents sticking and makes slices neater. Cream butter and sugars: In a large bowl or stand mixer fitted with a paddle, beat the softened butter with the granulated and brown sugar on medium speed until pale and fluffy, about 2–3 minutes. This aeration helps the bars rise slightly and improves texture. Add eggs and vanilla: Add eggs one at a time, mixing well after each addition, then beat in vanilla. Scrape the bowl sides periodically to ensure even incorporation and avoid streaks of butter. Combine dry ingredients: In a separate bowl, whisk together the all-purpose flour, baking soda, and salt. With the mixer on low, gradually add the dry ingredients to the wet until just combined—avoid overmixing to keep the center tender. Fold in chips and candies: Using a spatula, fold in the chocolate chips and 1–1½ cups of M&Ms until evenly distributed. Reserve a small handful of candies to press on top for decoration. Press into pan and bake: Spoon the dough into the prepared pan and use an offset spatula or lightly floured hands to press it into an even layer. Press extra M&Ms on top for a festive look. Bake at 350°F for 20–25 minutes, until the edges are golden and the center is set but still soft. A toothpick inserted in the center should come out with a few moist crumbs. Cool and slice: Allow the slab to cool completely in the pan on a wire rack—about 60–90 minutes—then lift out via the parchment overhang and slice into 24 bars. Cooling completely prevents cracking and yields cleaner slices.

Storage Tips

Store cooled bars in an airtight container at room temperature for up to three days; add a piece of parchment between layers to prevent sticking. For longer storage, wrap individual bars tightly in plastic and place in a freezer-safe container for up to three months. Thaw at room temperature for about 30–60 minutes before serving; for a warm bite, microwave for 10–12 seconds. Avoid refrigeration which can dry the bars unless your kitchen is very warm—then cool in the fridge briefly to firm up the chocolate before packing.

Ingredient Substitutions

If you’re out of unsalted butter, swap salted butter and omit the added ½ teaspoon salt or reduce it slightly—taste your dough. For a slightly lighter bar, substitute up to ½ cup of all-purpose flour with whole-wheat pastry flour, but expect a nuttier flavor and denser crumb. Use dairy-free margarine and vegan chocolate chips to make these dairy-free and vegetarian-friendly, though texture and flavor will shift subtly. Nuts like chopped walnuts or pecans can replace half the chocolate chips for crunch—toast them first for more flavor.

Serving Suggestions

Serve these bars warm with a scoop of vanilla ice cream for an indulgent dessert, or arrange them on a festive platter dusted with powdered sugar for parties. They pair well with hot chocolate or coffee during holiday gatherings. For a brunch-style spread, cut into smaller squares and offer alongside fruit, shortbread, and spiced tea. Garnish with extra whole M&Ms or a light drizzle of melted white chocolate for a more polished presentation.

Cultural Background

One-pan bars and squares have long been a holiday staple in American baking—easy to scale, transport, and share. These M&M-studded bars blend classic chocolate chip cookie elements with the colorful tradition of seasonal candies. Candy-coated chocolates became popular in the U.S. in the mid-20th century, and pairing them with cookie dough is a modern twist that pays homage to the communal, celebratory nature of holiday baking.

Seasonal Adaptations

For winter variations, swap half the chips for chopped peppermint bark or stir in ½ teaspoon peppermint extract for a mint-chocolate profile. In other seasons, use pastel-colored candies for spring or orange-and-black M&Ms for Halloween. For a Valentine’s version, use red and pink candies and add a splash of almond extract. These simple swaps keep the base method the same while transforming the mood of the bars.

Meal Prep Tips

To prep ahead, bake the slab and freeze whole—thaw and slice when needed. For grab-and-go breakfasts or lunchbox treats, portion into single wrappers so you can pull one from the freezer each morning. When packing for an event, place waxed paper between layers to avoid sticking and stabilize stacks with a small parchment collar inside the box.

These cookie bars are an approachable, cheerful addition to holiday baking that reward very little fuss with big flavor. I hope they become a staple in your seasonal rotation—easy to make, easy to share, and always welcomed at the table.