Brown Butter M&M Cookie Bars

Thick and chewy M&M cookie bars with brown butter and dark chocolate chunks. Perfect for bake sales or a holiday cookie exchange.They are so easy and fast to make. It’s easy, no-chill cookie dough with a toasty brown butter base. This gives it so much flavor and has a great texture of chewy centers with crisp edges.

sliced cookie bars.

The top is decorated with more colorful M&M’s and a few extra chunks of dark chocolate!

You can make different versions of these cookie bars too like brown butter chocolate chip cookie bars and mini egg cookie bars.

Chewy M&M cookie bars

These buttery cookie bars are just like brown butter cookies but without the hassle of rolling individual chocolate chip cookies. The cookie dough is baked in an 8×8-inch (20x20cm) baking pan. The dough is made using melted butter so there is no need for a hand mixer or stand mixer.

It’s topped with a few extra M&M’s and chunks of semi-sweet chocolate or milk chocolate, then baked until golden brown. You can change the color theme of these cookie bars by switching up the m&m colors!

For Christmas M&M cookie bars, use the green and red M&Ms. Once cooled, it’s sliced into individual cookie pieces. 

close up of piece of cookie bar.

Brown butter

The base of these delicious cookie bars is based on espresso brown butter chocolate chip cookie recipe. Cookie bars made with brown butter really trump those made with regular butter when it comes to flavor.

Brown butter, also known as beurre noisette is simply butter that has melted, and then cooked a step further so that the milk solids in the butter caramelize. This gives a toffee flavor to the butter.

The depth of flavor in the melted butter depends on how much it is left to caramelize. Too little and the flavor will be too mild. However in the same regard, if you caramelize it too much, you run the risk of burning the milk solids and cooking off too much liquid which can affect the dough.

Brown butter is also amazing in brown butter swiss meringue buttercream!

a hand holding a cookie bar.

How to brown butter

In a saucepan over medium heat, let the butter melt completely. Avoid using a dark pan as you will struggle to see the caramelization of the butter and run the risk of burning it.

Once melted, let it cook further for around 3-4 minutes, stirring occasionally until the milk solids in the butter have caramelized into a deep amber color and the butter smells toasty.

Pour the hot butter into a mixing bowl, including all the caramelized solids at the bottom of the pan (they’re the best bits!). Allow it to cool down for 10 minutes before continuing with the recipe.

butter being poured from a saucepan into a white bowl.

Ingredients

These M&M chewy cookie bars are made with basic ingredients. The exact amounts are listed in the recipe card below, but here is a run-down. For these cookie bars, you will need –

  • Butter – Unsalted butter or salted butter can be used. The melted butter makes a chewy cookie bar.
  • Light brown sugar – this helps keep the cookie bar moist.
  • Granulated white sugar – adds a little crispiness to the edges.
  • Vanilla extract or paste
  • Egg- brings structure to the dough and texture.
  • All-purpose flour
  • Baking soda
  • Baking powder
  • M&Ms
  • A little semi-sweet chocolate chips or milk chocolate for the topping. This is optional, but the extra chocolate on top makes these cookie bars even better!

Method

Brown butter

Begin by browning the butter as that needs a little time to cool.

Let the butter melt in a small metal saucepan. Once melted, let it cook for around 3-4 minutes until the milk solids have caramelized and the butter smells nutty. Pour the browned butter into a large bowl and cool down for around 10 minutes.

Preheat the oven to 350°F (180°C.) Line an 8x8inch (20x20cm) baking pan with parchment paper.

Cookie dough

Once the butter has cooled, add in the brown sugar, granulated sugar, egg, and vanilla and mix it together well.

butter being poured into a bowl.
a bowl of egg and sugar.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.

Tip the dry ingredients into the wet ingredients and stir them with a rubber spatula until mainly all combined, but with a few streaks of flour remaining. Add in the M&Ms and stir until combined.

flour onto a bowl.
a spatula in dough.

Tip the cookie dough into the prepared baking dish.

Press dough down into the dish and smooth it out.

a bowl of colorful candies in cookie dough.
a hand pressing m&ms into dough.

Roughly chop the chocolate. Press the remaining M&Ms onto the cookie dough and top with chopped chocolate.

m&m covered cookie dough.

Baking

Bake the cookie bars for around 22-25 minutes until the edges are browned and the top is set and light golden brown, but still a bit soft in the middle. How fast it bakes will depend on your oven.

Let the cookie bar cool in the tin for 15 minutes before removing the cookie slab from the pan and letting it cool completely on a wire rack. Use the parchment paper to lift the cookies out. The cookies will be quite soft while still warm but they will firm up as they cool to room temperature.

To serve, slice the cookies into individual cookies with a sharp knife. Slice 4 rows horizontally and 4 rows vertically to create 16 pieces.

sliced cookie bars.

Storing

Store leftover cookie bars in an airtight container for up to 5 days. The dough can also be frozen for future cookies.

Press it into the lined pan and freeze until stiff. Remove it from the pan and wrap it in plastic wrap or place it in an airtight container and freeze for up to 3 months.

When ready to bake, place the frozen cookie slab into the pan, lined with parchment paper. It can be baked from frozen but may need an extra minute or two of baking time.

bitten cookie.

More easy recipes

For more cookie bar recipes and other sweet treats, check out:

sliced cookie bars.

Brown Butter M&M Cookie Bars

Yield: 16
Prep Time: 15 minutes
Cook Time: 25 minutes
Total Time: 40 minutes

Thicky and chewy M&M cookie bars with brown butter and dark chocolate chunks.

Ingredients

  • 170g (¾ cup) unsalted butter
  • 150g (¾ cup, packed) soft brown sugar
  • 50g (¼ cup) granulated sugar
  • 1 large egg
  • 1 ½ teaspoons vanilla paste or extract
  • 218g (1 ¾ cups*) all-purpose flour

  • ½ teaspoon baking powder
  • ½ teaspoon baking soda
  • ½ teaspoon salt
  • 170g (1 cup) M&Ms, plus more for topping
  • 30g (1oz) semi-sweet chocolate (optional), for topping

Instructions

  1. Let the butter melt in a small metal saucepan. Once melted, let it cook further for around 3-4 minutes until the milk solids have caramelized and the butter smells nutty. Pour the browned butter into a large bowl and allow it to cool down for around 10 minutes.
  2. Preheat the oven to 350°F (180°C.) Line an 8x8inch (20x20cm) baking pan with parchment paper.
  3. Once the butter has cooled, add in the brown sugar, granulated sugar, egg, and vanilla and mix it together well.
  4. In a small bowl, whisk together the flour, baking powder, baking soda, and salt.
  5. Tip the dry ingredients into the wet ingredients and stir them with a rubber spatula until mainly all combined, but with a few streaks of flour remaining. Add in the M&Ms and stir until combined.
  6. Tip the cookie dough into the prepared baking dish.
  7. Press dough down into the dish and smooth it out.
  8. Roughly chop the chocolate. Press the remaining M&Ms onto the cookie dough and top with chopped chocolate.
  9. Bake the cookie bars for around 25 minutes or until the edges are browned and the top is set and golden brown, but still slightly soft in the middle. This may take less or more time depending on your oven.
  10. Let the cookie bar cool in the tin for 15 minutes before removing the cookie slab from the pan and letting it cool completely on a wire rack. The cookies will be quite soft while still warm but they will firm up as they cool to room temperature.
  11. To serve, slice the cookies into individual cookies with a sharp knife. Slice 4 rows horizontally and 4 rows vertically to create 16 pieces.

Notes

*The cup sizes provided are US-sized cups. Note that these are smaller than metric cups. For best results, use grams.

Nutrition Information:
Yield: 16 Serving Size: 1
Amount Per Serving: Calories: 220Total Fat: 12gSaturated Fat: 7gTrans Fat: 0gUnsaturated Fat: 4gCholesterol: 36mgSodium: 137mgCarbohydrates: 26gFiber: 1gSugar: 21gProtein: 2g

This is an informational estimate only. I am not a certified Dietitian or Nutritionist

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