This tray of Christmas cookie bars has been my family's holiday shortcut for years — the kind of dessert I make when hosts ask me to bring something that will disappear in minutes. I first developed this version when I needed a portable sweet for a school holiday party: I wanted the flavor and chew of a classic cookie but in an easy-to-slice pan dessert that could be served on paper plates without a frosting mess. The result is a buttery, slightly chewy base with pockets of chocolate and the festive crunch and color of M&M’s. Kids always reach for these first, and adults love that they slice cleanly and travel well.

What makes these bars special is the balance of textures and the simplicity. The dough is dense enough to hold mix-ins without sinking, and the short bake time keeps the center tender while the edges caramelize to a pleasant golden brown. I usually use high-quality semi-sweet chips and a familiar brand of M&M’s to get that classic candy shell pop. Baking a batch fills the kitchen with butter and vanilla aromas that instantly feel like the holidays — a smell that always prompts friends and family to ask for the recipe.

Ingredients

• Butter (3/4 cup; 1 1/2 sticks): Use unsalted, softened butter for controlled seasoning. I prefer a European-style butter when available for a richer flavor, but standard unsalted works perfectly. Softening to room temperature ensures smooth creaming with sugars.
• Vanilla extract (2 teaspoons): Pure vanilla adds depth; I use Nielsen-Massey or another pure extract. It brightens the buttery base and complements the chocolate.
• Granulated sugar (2/3 cup): Balances sweetness and helps with spread and slight crisping at the edges.
• Brown sugar, packed (1 cup): Use light brown sugar for a subtle molasses note that keeps the bars chewy and moist.
• Eggs (2 large): Room-temperature eggs incorporate more evenly and help bind the dough.
• All-purpose flour (3 cups): Provides structure. Spoon and level into the cup to avoid packing too much flour.
• Baking soda (1 teaspoon): Gives a touch of lift while keeping the texture bar-like rather than cakey.
• Salt (1 teaspoon): Enhances the sweet flavors; reduce only if using salted butter and you prefer less salt.
• Semi-sweet chocolate chips (1 cup): Choose a mid-range chip like Ghirardelli or Nestlé Toll House for reliable melt and chocolate flavor.
• Christmas M&M’s (1 cup total; 1/2 cup for dough, 1/2 cup for topping): Dividing them prevents all the candy from melting into the dough and keeps a colorful topping.
• White chocolate chips (1/4 cup for topping): Optional but recommended for visual contrast and a creamy sweetness on top.

Instructions

Preheat and prepare: Preheat your oven to 325°F and prepare a 9×13-inch baking pan by lightly greasing it or lining with parchment paper, leaving an overhang for easy removal. The lower temperature prevents over-browning while baking the thick dough through. If using parchment, don’t skip the spray to keep slices intact when you lift them out. Cream butter and sugars: In a large bowl, cream the softened butter with both the brown sugar and granulated sugar on medium speed for about 3 minutes until light and fluffy. Proper creaming incorporates air for a tender crumb; scrape the bowl sides once or twice to ensure even mixing. Add eggs and vanilla: Add the eggs one at a time, mixing after each until fully incorporated, then stir in vanilla. Use room-temperature eggs to avoid seizing the butter; the mixture should look smooth and slightly glossy. Combine dry ingredients: Whisk together the flour, baking soda, and salt in a separate bowl. Gradually add the dry mix to the wet ingredients on low speed and mix until a thick dough forms. Avoid overmixing to keep the bars tender rather than tough. Fold in mix-ins: Gently fold in 1 cup of semi-sweet chocolate chips and 1/2 cup of the Christmas M&M’s by hand so they are evenly distributed without crushing the candies. Press and top: Spread the dough evenly into the prepared pan, using an offset spatula or damp hands to smooth the surface. Sprinkle the remaining 1/2 cup of M&M’s and the 1/4 cup white chocolate chips over the top for color and texture before baking. Bake: Bake in the preheated 325°F oven for 26–30 minutes, until the edges are lightly golden and a toothpick inserted near the center comes out with a few moist crumbs. Oven times vary; check at 26 minutes to avoid over-baking. Cool and slice: Remove the pan from the oven and cool completely on a wire rack. When cooled, lift the slab out using the parchment overhang and slice into squares with a sharp knife, wiping the blade between cuts for neat edges.

Storage Tips

Store cooled bars in an airtight container at room temperature for up to 48 hours. For longer storage, wrap the slab tightly in plastic wrap and foil, then freeze for up to 3 months. When freezing individual portions, separate layers with parchment to prevent sticking. To reheat while preserving texture, place slices on a baking sheet and warm at 300°F for 5–8 minutes, or microwave single portions for 10–15 seconds if you prefer a softer, gooey center.

Ingredient Substitutions

To reduce dairy, use a vegan stick-style margarine and dairy-free chocolate chips (note the flavor and texture will differ). For gluten-free, substitute a 1-to-1 gluten-free flour blend with xanthan gum and measure carefully for similar structure. Swap brown sugar for coconut sugar for a deeper caramel note, but expect a slightly drier texture. Replace semi-sweet chips with chopped dark chocolate for a richer bar, or use peanut butter chips for a nutty variation. If avoiding candy shell colors, use chopped milk chocolate and reserve some chips for topping.

Serving Suggestions

Serve bars on a festive platter with a dusting of powdered sugar or a drizzle of melted white chocolate. They pair well with hot cocoa, coffee, or mulled cider at holiday gatherings. For a dessert plate, add a scoop of vanilla ice cream and warm a slice slightly to create a contrast of cold and warm textures. Garnish with fresh cranberries or rosemary sprigs for a holiday presentation that looks more elaborate than the simple preparation suggests.

Seasonal Adaptations

While these are perfect for Christmas with M&M’s, adapt the toppings seasonally: pastel candies for Easter, red and pink candy for Valentine’s Day, or orange and brown candies for autumn. In winter, stir in chopped toasted pecans and a pinch of cinnamon for a spiced variation. For summer barbecues, switch to mini chocolate chips and add 1/2 cup chopped dried cherries for a bright fruit note that pairs well with the buttery base.

Meal Prep Tips

Make a double batch and freeze half for quick entertaining: bake, cool, and cut into portions, then flash-freeze on a tray before packing into freezer bags. Label with date and contents. For quick weekday treats, slice and keep in the fridge; individual bars can be wrapped and placed in lunch boxes for a festive snack. If you plan to transport, place parchment between layers and keep chilled to prevent candy melting in warm cars.

These bars are a reliable, crowd-pleasing holiday treat that simplify festive baking without sacrificing flavor. Bake a batch, share plates with neighbors, and enjoy how a simple pan of cookie bars can turn everyday moments into holiday memories.