This pan of Christmas cookie bars started as a way to get all of the joy of holiday cookies without baking dozen trays. I discovered the formula one December when I needed a bake sale contribution and had only one 9 by 13 pan in the kitchen. The result was a tray of rich, buttery bars that stayed soft in the center and developed lightly golden edges. My family loved how the M&M’s kept their bright colors and the white chocolate on top added a creamy contrast. These squares quickly became my go to for school parties and impromptu cookie exchanges.

The texture is what keeps people coming back. The base is a tender, shortbread like dough because of the generous butter and brown sugar. Inside you find pockets of semi sweet chips and a scattering of Christmas M&M’s that give crunch and color. Baked just until the edges turn light golden you get a slightly chewy interior that slices cleanly once cooled. This recipe is forgiving, easy to scale, and great for baking with kids because the dough is straightforward and there is sticky, colorful reward when they add the topping.

Ingredients

• Butter 3/4 cup softened 1 and 1/2 sticks Use unsalted butter at room temperature for control over salt content. If your butter is too cold the dough will be harder to cream while if it is too warm the texture can become greasy.
• Vanilla extract 2 teaspoons Pure vanilla extract adds depth. I prefer Nielsen Massey for a dependable, clean flavor but any pure extract works well.
• Granulated sugar 2/3 cup Adds lift and crispness around the edges. Measure by spooning into the cup and leveling for accuracy.
• Eggs 2 large Use large eggs at room temperature so they incorporate smoothly without shocking the creamed butter.
• All purpose flour 3 cups Spoon and level into the measuring cup to avoid packing and a drier final product. This amount yields a sturdy yet tender bar.
• Salt 1 teaspoon Balances sweetness and enhances the butter flavor. If using salted butter reduce added salt slightly.
• Brown sugar 1 cup packed Light brown sugar keeps the center moist and contributes a gentle caramel note. Pack into the measuring cup and level off.
• Semi sweet chocolate chips 1 cup Creates melty pockets throughout. Use good quality chips like Ghirardelli for deep chocolate flavor.
• Baking soda 1 teaspoon Gives a modest lift so the bars rise just enough without becoming cakey.
• Christmas M&M’s 1 cup divided Use festive colors. Add half to the dough and reserve half for the top so colors stay bright after baking.
• White chocolate chips 1/4 cup for topping Adds sweet contrast and a creamy, slightly floral note that pairs beautifully with the milk chocolate.

Instructions

Preheat and prepare pan: Set the oven to 325 degrees Fahrenheit and grease a 9 by 13 inch baking pan or line it with parchment to lift the bars out easily after cooling. This moderate temperature helps the bars bake evenly with golden edges and a tender center. Cream butter and sugars: In a large bowl use a stand mixer with the paddle attachment or a hand mixer on medium speed to cream the softened butter with the brown sugar and granulated sugar for about three minutes until the mixture is light in color and fluffy. Scrape down the sides once so all ingredients are evenly incorporated. Add eggs and vanilla: Beat in the eggs one at a time and then add the vanilla extract. Continue mixing until the batter is smooth and glossy. If the mixture looks curdled a brief mix will bring it back together once the flour is added. Combine dry ingredients: Incorporate the baking soda and salt into the wet mixture and then add the flour gradually. Mix on low speed just until a dough forms. Avoid over mixing to keep the bars tender rather than tough. Fold in chips and candies: Gently fold in one cup of semi sweet chocolate chips and one half cup of the M&M’s using a spatula so the candies do not lose their color completely. Assemble and top: Press the dough evenly into the prepared pan with an offset spatula. Scatter the remaining half cup of M&M’s and the white chocolate chips on top, pressing lightly so they adhere but still sit visible on the surface. Bake and cool: Bake for 26 to 30 minutes until the edges are lightly golden and the center is set but not dry. Allow the pan to cool completely on a rack before slicing into squares to avoid crumbly pieces.

Storage Tips

Store the cooled bars in an airtight container at room temperature and place a sheet of parchment between layers to prevent sticking. For longer storage freeze individual squares on a tray then transfer to a freezer safe bag for up to three months. To reheat frozen bars thaw in the refrigerator overnight and warm in a 300 degree Fahrenheit oven for five to seven minutes if you want the chips to return to a slightly melty texture. Quality indicators include a fresh buttery aroma and intact colors on the M&M’s.

Ingredient Substitutions

If you need a dairy free version use a vegan butter substitute and dairy free chocolate chips and confirm the M&M’s are dairy free which some varieties are not. For a chewier result replace one quarter cup of the all purpose flour with rolled oats ground briefly in the blender. To reduce sweetness use dark chocolate chips instead of semi sweet and omit the white chocolate on top. Keep ratios similar so the dough consistency remains the same.

Serving Suggestions

Serve warm with a dusting of powdered sugar for a festive look. These bars pair well with hot cocoa, strong coffee, or mulled cider. For a dessert platter combine with ginger snaps and spiced nuts. Garnish with a few extra M&M’s on each square for parties so everyone recognizes the treat.

Cultural Background

Cookie bars are an American adaptation of handheld cookie traditions that simplify baking by using one pan. They became popular for bake sales and school functions because they reduce hands on time while delivering the same flavors as drop cookies. Decorating with holiday candies like M&M’s is a modern twist that adds color and child friendly appeal during seasonal celebrations.

Seasonal Adaptations

Adapt for other holidays by swapping the M&M color palettes to match themes. In winter add chopped toasted pecans and a sprinkle of sea salt for a more sophisticated holiday offering. For summer barbecues swap the white chocolate for butterscotch chips and add toasted coconut for a tropical touch.

Meal Prep Tips

Prepare the dough up to two days ahead and cover the bowl in the refrigerator. Press into the pan and top immediately before baking. For grab and go breakfasts cut into smaller squares and pack individually in reusable bags. Use an insulated container to keep bars slightly warm for a few hours at events.

These Christmas cookie bars are a dependable holiday staple. They are quick, portable, and crowd pleasing which makes them one of my favorite go to sweets when I need something festive without fuss. Try the basic formula once and you will find yourself adapting it for every occasion.