This batch of Christmas M&M cookie bars is the holiday tray staple that quietly became my family’s favorite. I first landed on this formula one December when I wanted something faster than drop cookies but with the same chewy, buttery comfort. The first pan I pulled from the oven had a glossy, crackled top and a soft, slightly gooey center — my kids declared it the best treat I’d ever made and requested it at every holiday gathering since. It’s the kind of sweet that fills the kitchen with buttery, vanilla-sugar aromas and makes people linger.

What makes these bars special is their texture: a crisp edge with a tender, almost cookie-dough center that holds a satisfying chew. The brown sugar gives depth and slight caramel notes while the red-and-green M&M’s add both crunch and a festive pop of color. The recipe is forgiving — you can mix it in one bowl, press it into a pan, and bake. Because it’s quick and uses pantry staples, I reach for it when I need a crowd-pleasing dessert in a hurry. Over the years I’ve learned a few little tricks — from how long to cool before slicing to how to avoid faded candy colors — and I’ll share those so your pan comes out picture-perfect and delicious.

Ingredients

• All-purpose flour (2 cups): The structure of the bars — use a reliable brand like King Arthur or Pillsbury for consistent results. Spoon and level the flour when measuring to avoid dry, crumbly bars.
• Packed brown sugar (1 cup): Adds moisture and chew. Use light brown for a classic caramel hint; dark brown will give a deeper molasses flavor.
• Granulated sugar (1/2 cup): Balances sweetness and helps create a slightly crisp crust on top.
• Unsalted butter (1 cup, softened): Softened to room temperature — not melted. Butter adds richness and helps the bars brown; use high-quality butter for best flavor.
• Baking soda (1 teaspoon): Gives a gentle lift and chew; make sure it’s fresh for reliable rise.
• Salt (1/2 teaspoon): Enhances flavor — if using salted butter, reduce added salt slightly.
• Large eggs (2): Bind the dough and add tenderness; room temperature eggs incorporate more smoothly.
• Vanilla extract (1 teaspoon): Real vanilla brings warmth and depth; avoid imitation if you can.
• Christmas M&M’s (1 cup): Use the seasonal red and green candies for festive color; reserve a few for the top so the bars look bright after baking.
• Chocolate chips (1/2 cup): Semi-sweet chips add pockets of melty chocolate; mini chips are ideal if you want even distribution.

Instructions

Prepare and preheat: Preheat the oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment, leaving an overhang to lift the bars out easily. Softened butter should feel like room-temperature spreadable butter but not oily; this helps incorporate air for a lighter texture. Mix the wet ingredients: In a large bowl, cream the softened butter with the brown sugar and granulated sugar until light and a bit fluffy — about 2 to 3 minutes with a hand mixer. Add the eggs one at a time, mixing until fully incorporated, then add vanilla. Scrape the bowl so there are no streaks of butter or sugar. Combine dry ingredients: Whisk the flour, baking soda, and salt together in a separate bowl so the leavening disperses evenly. This prevents pockets of baking soda that can cause uneven rise or a soapy flavor. Form the dough: Fold the dry ingredients into the wet mixture with a sturdy spatula until just combined. Overmixing develops gluten and can make bars tough; stop when you no longer see streaks of flour. Fold in the chocolate chips and most of the M&M’s, reserving a few to press on top. Press and bake: Press the dough evenly into the prepared 9x13 pan — use a spatula lightly oiled or parchment to avoid sticking. Press the reserved M&M’s on top for visual appeal. Bake 18–22 minutes: edges should be set and lightly golden, center still slightly soft to the touch. An inserted toothpick may come out with a few moist crumbs; avoid baking until completely dry to keep bars chewy. Cool and slice: Cool the pan on a wire rack for at least 30 minutes to let the bars firm up. Use the parchment overhang to lift the slab out, then slice into 12 or 15 squares with a sharp knife. For cleaner edges, chill the slab 20 minutes before slicing.

Storage Tips

Store cooled bars in a single layer in an airtight container at room temperature for up to 3 days. If stacking, separate layers with parchment to prevent sticking. For longer storage, freeze individual bars on a tray until firm, then transfer to a freezer bag for up to 3 months. Thaw at room temperature for 30–60 minutes before serving. To refresh slightly stale bars, warm for 10–12 seconds in the microwave or 5 minutes at 300°F in the oven to revive chew and soften chocolate.

Ingredient Substitutions

For dairy-free, replace butter with 1 cup vegan butter or solid coconut oil (the bars will be slightly more crumbly). Use egg replacer or 1/4 cup applesauce per egg for an egg-free option, though texture will be less chewy. Swap M&M’s for chopped seasonal candy or sprinkles; use gluten-free 1:1 flour blend to make them gluten-free (note that texture may vary slightly). For a nuttier bar, stir in 1/2 cup chopped pecans or walnuts.

Serving Suggestions

Serve warm with a scoop of vanilla ice cream for a dessert that feels indulgent. For holiday parties, arrange bars on a platter with sprigs of fresh rosemary for a festive look. Pair with coffee or hot cocoa; small squares are perfect with afternoon tea. For gifting, stack 3–4 bars in clear cellophane and tie with ribbon for an easy homemade present.

Cultural Background

Cookie bars — sometimes called traybakes — are a practical American adaptation of traditional drop cookies. They became popular because they save time: you get the same cookie flavor with less labor and fewer baking sheets. The idea of adding colorful candies to baked goods traces back to mid-20th-century candy innovations; seasonal M&M’s help tie this version to contemporary holiday aesthetics while keeping the nostalgic cookie experience.

Seasonal Adaptations

For winter warmth add 1 teaspoon ground cinnamon and a pinch of nutmeg to the dry mix. For a spring variation, swap out holiday M&M’s for pastel ones and add 1/2 cup shredded coconut. Around Halloween use orange and black candies and a tablespoon of pumpkin spice for seasonal flair. These swaps allow the same base to celebrate different holidays.

Meal Prep Tips

Prepare the dough up to 24 hours ahead and keep covered in the refrigerator; press into the pan and bake when ready. You can also freeze the unbaked pressed pan wrapped tightly; bake from frozen, adding 4–6 minutes to the bake time. Portion bars into individual wraps for grab-and-go breakfasts or snacks that travel well and stay fresh when refrigerated.

Success Stories

I once took a pan of these to a family reunion and an uncle who rarely comments on sweets asked for the recipe — that’s my unofficial seal of approval. A neighbor used them to raise funds for a local school bake sale and reported they were the top-seller. I keep notes about small tweaks people loved: pressing extra M&M’s on top for kids, and giving a 10-minute chill before slicing for cleaner edges when packing.

Make these bars your own — whether you stick to the classic red-and-green look or swap mix-ins, they’re designed to be forgiving, festive, and utterly shareable. Enjoy baking and sharing a pan of holiday cheer.