Soft Sugar M&M Cookie Bars

4.91 from 44 votes

M&M Cookie Bars!! One of my favorite desserts of all times. And also be warned – one is NOT to be left alone with a pan of these!

Prep Time5

Cook Time40

Total Time45

Course: Dessert

Cuisine: American

Servings: bars

Author: Gaby Dalkin

Equipment

Ingredients

1 cup butter melted
2 cup light brown sugar
4 teaspoons vanilla extract
2 large eggs
2 cups all purpose flour
1 teaspoon baking powder
¼ teaspoon of baking soda
1 cup Milk Chocolate M&M’s plus extra for garnish
Maldon sea salt optional

Instructions

Preheat oven to 350 degrees.
In a large bowl, combine the melted butter and brown sugar and mix with a wooden spoon for 1 minute until combined. Add the vanilla and eggs, making sure to scrape down the sides of the bowl, and mix until fully incorporated.
Add the dry ingredients into the bowl and slowly mix until just combined. The batter will be a bit stiff, but that's normal. Fold in 1 cup of the Milk Chocolate M&M’s.
Spray a 9x9 metal baking pan (see note above) with baking spray and line it with parchment paper. Spoon the batter into the prepared baking sheet and sprinkle with the remaining Milk Chocolate M&M’s and Maldon sea salt if desired and transfer it into the oven. Bake for 35-40 minutes. Once the bars have baked, remove them from the oven and let cool for at least 2 hours before cutting and serving.

Notes

Use room-temperature butter. Soft (not melted!) butter creams better with the sugars and gives you that thick, chewy cookie-bar texture instead of something cakey.
Don’t skimp on the brown sugar. Brown sugar adds moisture and chew. It’s what makes these bars taste rich and caramel-y. The combo of white + brown is key.
Mix just until combined. Overmixing = tough bars. Once the flour disappears, you’re done. Fold in the M&Ms gently so they don’t crack apart.
Line your baking dish. Parchment paper with a little overhang makes it so easy to lift out the entire slab and cut perfect squares. No sticking, no crumbling.
Press the dough evenly. Use your hands or an offset spatula to spread the dough to the edges. Even thickness = even baking.
Add extra M&Ms on top. Press a handful into the surface before baking so the colors stay bright and pretty, it’s the bakery-style finishing touch.
Don’t overbake! Pull them when the center still looks slightly underdone. They’ll set as they cool and stay soft and chewy instead of dry.
Cool completely before slicing. This is the hardest part, but it’s what gives you clean edges and bars that hold together instead of crumbling into a cookie avalanche.
Switch up the mix-ins. Mini chocolate chips, pretzels, peanut butter chips, chopped nuts, whatever you love. M&Ms play well with others.
Store them properly (if they last). Keep in an airtight container to maintain that soft chew. Warm them for 10 seconds if you want a gooey, fresh-from-the-oven moment.
Use a 9x9 pan. Don't try and do it in a 9x13 or an 8x8... it won't be the same. Trust me - there's a reason I developed it this way! And a glass or ceramic baking dish doesn't retain heat the same way a metal baking dish does... so use a metal baking dish! And 8x8 (while it's the same shape is only 64 square inches and a 9x9 is 81 inches. So that will WILDLY affect baking time.
After the baking time - LET THESE SET FOR 2 HOURS. These cookie bars might look a little under-baked but they need time to finish residual baking once they come out of the oven.

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