Delicious and Gooey Monster Brookies

June 16, 2023

Monster Brookies – a rich and delicious brownie layer, topped with peanut butter, a chocolate chip cookie layer and mini M&Ms.

Stack of brookie bars

Monster Brookies

Happy Friday! It’s been a busy few weeks over here, but I finally got into the kitchen this week and whipped up something that has all of my favorite things. My new Monster Brookies are a combination of a rich and decadent brownie layer, a peanut butter layer, a chocolate chip cookie layer, with mini M&Ms and flakey salt.

These bars are going to rock your world!

I’m not even going to get fancy with a huge blog post because you just need to make these.

Brookies cut into squares.

Here’s everything you need to know:

  • You’re making a brownie recipe and a chocolate chip cookie recipe.
  • You’ll bake the brownie layer on its own for 15 minutes and then pile everything on top and bake again.
  • These bars are still kinda gooey when they are done baking – give them at least an hour to cool and set.
  • Don’t worry that the top looks golden brown and a little crisp. The center will still be soft and you’ll have an awesome texture combo.
  • These store great in an airtight container at room temperature. You can microwave them next day for that gooey center, or serve at room temp for a more solid texture.
Stack of brookies.

Monster Brookies

5 from 24 votes
Gooey brownies with peanut butter, a chocolate chip cookie layer, mini M&Ms and flakey salt.
Servings 24 bars


For the Brownie Layer

  • 1 1/2 cups (180 g) all-purpose flour
  • 3/4 cup (88.5 g) good quality dark chocolate cocoa powder
  • 1 teaspoon (6 g) salt
  • 1 cup (226 g) unsalted butter
  • 1 cup (180 g) bittersweet chocolate chips
  • 2 cups (440 g) light brown sugar, packed
  • 4 eggs
  • 2 teaspoons (8.4 g) vanilla extract
  • 1 cup (180 g) semi-sweet chocolate chips

For the Cookie Layer

  • 3/4 cup (169.5 g) unsalted butter, at room temperature
  • 1/2 cup (100 g) granulated sugar
  • 1/2 cup (110 g) brown sugar, packed
  • 1 egg, at room temperature
  • 1/2 teaspoon (2.1 g) vanilla extract
  • 1 3/4 cups (210 g) all-purpose flour
  • 1 teaspoon (4 g) baking soda
  • 1 teaspoon (6 g) salt
  • 1 cup (180 g) semi-sweet or dark chocolate chips

Fillings and Garnish

  • 1 cup (250 g) peanut butter, melted
  • 1/2 cup (112 g) mini M&Ms
  • Flakey salt


For the Brownie Layer

  • Preheat your oven to 350 degrees F. Spray a 9″ x 13″ baking dish with nonstick spray. Line the bottom and sides with parchment paper. Spray again. Set aside.
  • In a medium size mixing bowl, whisk together the flour, cocoa powder, and salt. Set aside.
  • In a medium size saucepan, melt the butter and the bittersweet chocolate chips until smooth. Remove from the heat and allow to cool for about 5 minutes.
  • Add the brown sugar to the butter and chocolate mixture and stir until smooth.
  • Add the eggs, one at a time, stirring well between each addition.
  • Stir in the vanilla.
  • Add the flour mixture and stir until no streaks of flour remain.
  • Fold in the 1 cup of the semi-sweet chocolate chips.
  • Pour the batter into the prepared pan.
  • Bake the brownies for 15 minutes.
  • While the brownies bake, make the cookie dough. (Instructions below)
  • When the 15 minute timer is up, remove the pan from the oven. Pour the melted peanut butter on top and gently spread into an even layer.
  • Using your hands, break apart the cookie dough (instructions below) and drop on top of the peanut butter and brownie. This does not need to be spread out. It will spread as it cooks.
  • Evenly sprinkle the mini M&Ms on top.
  • Bake for 30 minutes more minutes.
  • The top of the cookie layer will be golden brown. Don’t let that scare you that it’s over cooked. The centers will still be gooey and you’ll get a delicious crunch with each bite, as well.
  • Remove the pan from the oven and sprinkle on the salt.
  • Allow the bars to cool in the pans for at least an hour.
  • The centers will still be gooey after they cool for an hour. If you want the centers more set, allow the bars to sit for an additional hour or two.

For the Cookie Layer

  • In the bowl of an electric mixer fitted with the paddle attachment beat the butter until smooth.
  • Add the sugars and beat until light and fluffy, about 2 minutes. Scrape down the sides of the bowl.
  • Add the egg and mix until well incorporated. Scrape down the sides of the bowl. Add the vanilla and mix for about 30 seconds.
  • With the mixer on low speed, add the flour, baking soda, and salt. Mix until combined. 
  • Stir in the chocolate chips.
Course: Dessert
Cuisine: Bars
Keyword: Brookies, Brownies, cookies, Monster Brookies

Join the Conversation

  1. It was the kid. Totally the little one. The kid in the Instagram reel when her eyes said everything about how awesome these were! So I knew I needed them in my life. These turned out perfect despite my chocolate/butter/sugar mixture never getting totally smooth. I did find sitting overnight was best – still plenty gooey. This made a bunch because they are monstrous in size.

  2. I am so excited to try this recipe! I am hoping to make it today for father’s day but just noticed I have no bittersweet chocolate. Is there anything I can substitute it with?

    1. Sorry I’m just seeing this. You can use semi-sweet.

  3. 5 stars
    My husband said this was the single best thing he has ever eaten in his lifetime and I have to agree with him, every bite of this was perfection🤤 Thank you for sharing!!!

  4. Joselyn Pikciunas says:

    5 stars
    I love brownies. They are my favorite dessert. And I’ve been patiently waiting for Courtney to find a brownie recipe she loves! This recipe is AMAZING. I scrapped the cookie part and just made the brownie part in an 8×10 pan. It is absolutely *PERFECT*. Fudgy, but not too gooey and not too cakey. The chocolate flavor is so intense and amazing, and they are not overly sweet. The top got perfectly chewy, and the inside stayed super fudgy. I used a mixture of Ghirardelli bittersweet and semi sweet chocolate bars for the brownies. Courtney, these are amazing!! Thank you!!

    1. This makes me so happy!! Thank you!!

  5. 5 stars
    These are perfect. The mix of chocolate, cookie, pb, and m&m’s are perfection. Everyone at our gathering raved about them for days. They are rich but SO good. And sorry not sorry, Courtney, but good warmed up with vanilla ice cream! I also had extra brownie mixes from Ghirardelli that I used and it tasted great still!

  6. 5 stars
    These were pure perfection! I assumed they would taste good, but they exceeded my expectations. I will make these again and again. I sent half the batch to work with my husband and he said his coworkers devoured them. The only change I made was to add oats to the cookie dough, because to me monster cookies have to have oats. If anyone else had the same thought, I added 1/2 C. of rolled oats and it wasn’t nearly enough. It really wasn’t missed though because these tasted phenomenal.

  7. If i wanted to make this without the peanut butter in the middle would it still work?

  8. 5 stars
    These were delicious! I would definitely make them again.

    A typical monster cookie has oatmeal in it. I’m wondering if this could be done with an oatmeal cookie top or if it wouldn’t go well with the brownie layer?

    1. Feel free to!

    2. 5 stars
      These are amazing! I have definitely made the cookie with some oatmeal added and did less flour. They turned out great!

  9. Yum! Would love to see/try Monster Cookie Cake too! I know if you were to create one it would be exquisite!

  10. 5 stars
    Amazing, like all your recipes (peanut butter Oreo cake is heaven)!
    If I want to turn this into a round dish, would you recommend splitting between two round cake pans or just one?
    And what would you adjust the baking times to?

    1. Two! It’s very thick

  11. 5 stars
    I can’t even count how many times I’ve made these – a hit every single time. The brownie layer is so good – do you think it would stand up as a brownie recipe on its own?

  12. 5 stars
    We made these for easter and swapped out the m&m for crushed up Cadbury mini eggs. It was delicious 😋

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