A delicious hybrid of fudgy brownies and chocolate chip cookies, these moist and chewy high altitude chocolate chip cookie brownies have a layer of dark chocolate fudge brownies, with chocolate chip cookie dough baked right on top. Sprinkle with flaky salt for a tempting treat that no one can resist!
Looking for more cookie bar recipes? Don’t miss my chocolate chip skillet cookie, frosted sugar cookie bars, millionaire’s shortbread, and cookie butter blondies.
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Why You’ll Love These Brownies
Two Favorite Treats in One. When you don’t want to choose between a brownie or a cookie, you can have both with these tempting bars.
So Easy to Make. Even though you’re making brownie batter and cookie dough, both are very easy to make. They’re both quick to mix up with just a bowl and spoon, no mixer needed.
Stays Soft for Days. Kept in an airtight container, these brownies don’t dry out, staying soft, moist and fresh.
See the recipe card at the end of the post for the full ingredients list and instructions.
Ingredients
Cookie Layer
Based off my favorite chocolate chip cookies recipe, the cookie layer is soft, with a perfect balance of salty and sweet flavors.
- Unsalted Butter. Adds richness, moisture and flavor to the cookies.
- Granulated Sugar + Dark Brown Sugar. Adds sweetness and moisture, as well as subtle hints of caramel and molasses from the brown sugar.
- Vanilla Extract. Flavor.
- Egg Yolk. Gives the cookies structure and leavens the dough a little.
- All-Purpose Flour. Adds structure and stability so the cookie doesn’t spread too much.
- Coarse Kosher Salt. A good amount of salt is essential in chocolate chip cookies to enhance the flavor of the chocolate and balance the sweetness.
- Baking Soda. Leavens the dough.
- Chocolate Chips. Choose your favorite chocolate chips for these cookies, whether they’re milk, semi-sweet or dark.
Brownie Layer
My perfect fudge brownies are rich, dense, dark and so fudgy, not cakey. My method of mixing the batter gives them a beautiful, shiny crackly top that makes them so tempting.
- Cocoa Powder. Use a good-quality Dutch-processed cocoa powder, such as Rodelle. It’s what gives the brownies that rich, warm dark chocolate color, and the bitterness of the cocoa powder plays off the sugar to create a perfect balance.
- Chocolate. The melted chocolate adds more depth of flavor, but also makes a very fudgey texture, as well as contributes to the crackly top.
- Unsalted Butter. Adds richness and moisture.
- Sugar. Granulated sugar sweetens the brownies, balances the bitterness of the cocoa powder, and creates the shiny, crackly top on the surface of the brownies.
- Eggs. The eggs help to emulsify the batter, providing structure and leavening.
- All-Purpose Flour. I use just enough to pull the batter together, but not so much that it will dry out that wonderfully fudgey, gooey texture.
- Vanilla Extract. Good-quality vanilla is best, and is a beautiful complement to the chocolate.
- Espresso Powder. Optional, but a bit of espresso powder or instant coffee powder always enhances the flavor of chocolate really nicely.
- Salt. I use coarse Kosher salt in all of my cooking and baking, to balance the sweetness and enhance the flavors.
Instructions
Cookie Layer
- In a bowl, stir together the melted butter, sugar and brown sugar until smooth. Add the vanilla and egg yolk, and stir vigorously until smooth.
- Separately, combine the flour, salt and baking soda. Add to the butter mixture, and stir to form a dough. Let cool for 10 minutes (so that the chocolate chips don’t melt when you stir them in).
- Stir in the chocolate chips; the dough will be stiffer now than it was before cooling. Scoop the dough into 9 balls and refrigerate the dough balls while you make the brownie batter.
Brownie Layer
- In a large saucepan, melt the butter and sugar over medium heat. Once it begins to bubble, cook for two minutes. Remove from the heat and use a wooden spoon to stir in the chocolate chips and vanilla until melted and shiny; the mixture will be grainy. Let cool for 10 minutes (so that your eggs don’t scramble when you add them).
- Beat in the eggs, one at a time, until the mixture comes together into a smooth batter.
- In a bowl, sift together the cocoa powder, flour, salt and espresso powder. Add the dry ingredients to the batter and mix just until no dry streaks remain. The batter will be thick but spreadable.
Assembly and Bake
- Preheat the oven to 325 F. Line an 8 or 9-inch baking pan with parchment paper.
- Spread the brownie batter evenly into the pan.
- Smash the chilled cookie dough balls between your hands to flatten them a little, and arrange them on top of the brownie batter. Sprinkle the top with a few more chocolate chips.
- Bake the brownies on the center oven rack for 28-30 minutes, until slightly puffed and set.
- Cool the brownies completely (at least 6 hours or overnight) before cutting, if you want them to be set and slice cleanly when you cut them. You can speed up the cooling process by cooling them at room temperature for 1 hour, then refrigerating them for 1-2 hours.
- Lift the cooled brownies out of the pan by the parchment paper onto a cutting board to cut them into servings. If you like, sprinkle the top of the brownies with coarse finishing salt.
Be sure to read all of my BAKING FAQs where I discuss ingredients, substitutions and common baking questions, so that you can be successful in your own baking!
Frequently Asked Questions
How long do these brownies stay soft?
Store leftover brownies in an airtight container at room temperature for up to 3 days.
Can these be frozen?
You can wrap the brownies individually in plastic wrap and freeze for up to 3-6 months. Let thaw to room temperature for a quick treat.
Will this recipe work at any altitude?
It should! I test all of my recipes at Denver’s high altitude of 5,280 feet. But since this is a bar cookie, with very little leavening, there’s no reason it shouldn’t work well at sea level or low altitudes, too.
Can this recipe be doubled?
Yes, you can double the recipe for these chocolate chip cookie brownies and bake them in a 9×13 pan. They might need a few minutes longer to bake through.
What kind of chocolate chips do you use?
I prefer dark chocolate chips in both my chocolate chip cookies and brownies, but milk or semi-sweet will work, too.
What’s a good finishing salt to sprinkle on top?
I love Maldon, which is really flaky and pretty sprinkled on top of cookies.
Are these the same thing as slutty brownies?
They’re similar, but what a ridiculous name for a delicious cookie bar. “Slutty Brownies” are made with a layer of cookie dough, then a layer of Oreos, and lastly brownie batter, and they’re baked all together. If you’d like an interesting read about them, check out this article!
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Did you love today’s recipe? Please rate the recipe and let me know in the comments what you thought! Also, be sure to follow Curly Girl Kitchen on Instagram, and tag me when you try one of my recipes so I can see all your delicious creations!
High Altitude Chocolate Chip Cookie Brownies
All recipes on Curly Girl Kitchen are developed for high altitude at 5,280 feet.
Equipment
- 8 or 9 inch Square Baking Pan
Ingredients
Cookie Layer
- ¼ cup unsalted butter, melted
- 2 ½ tbsp granulated sugar
- 2 ½ tbsp dark brown sugar
- 1 tsp vanilla extract
- 1 egg yolk
- ¾ cup all-purpose flour, spooned and leveled
- ¼ tsp coarse Kosher salt (if using table salt, use half the amount)
- ¼ tsp baking soda
- ⅓ cup chocolate chips
Brownie Layer
- ½ cup unsalted butter
- 1 cup granulated sugar
- ½ cup semi-sweet or dark chocolate chips
- 2 tsp vanilla extract
- 2 large eggs
- ⅔ cup unsweetened, Dutch-processed cocoa powder
- ⅓ cup all-purpose flour, spooned and leveled
- ½ tsp coarse Kosher salt (if using table salt, use half the amount)
- 2 tsp instant espresso powder or instant coffee, optional
Instructions
Cookie Layer
- In a bowl, stir together the melted butter, sugar and brown sugar until smooth. Add the vanilla and egg yolk, and stir vigorously until smooth.
- Separately, combine the flour, salt and baking soda. Add to the butter mixture, and stir to form a dough. Let cool for 10 minutes.
- Stir in the chocolate chips; the dough will be stiffer now than it was before cooling. Scoop the dough into 9 balls and refrigerate the dough balls while you make the brownie batter.
Brownie Layer
- In a large saucepan, melt the butter and sugar over medium heat. Once it begins to bubble, cook for two minutes. Remove from the heat and use a wooden spoon to stir in the chocolate chips and vanilla until melted and shiny; the mixture will be grainy. Let cool for 10 minutes.
- Beat in the eggs, one at a time, until the mixture comes together into a smooth batter.
- In a bowl, sift together the cocoa powder, flour, salt and espresso powder. Add the dry ingredients to the batter and mix just until no dry streaks remain. The batter will be thick but spreadable.
Assembly and Bake
- Preheat the oven to 325 F. Line an 8 or 9-inch baking pan with parchment paper.
- Spread the brownie batter evenly into the pan.
- Smash the chilled cookie dough balls between your hands to flatten them a little, and arrange them on top of the brownie batter. Sprinkle the top with a few more chocolate chips.
- Bake the brownies on the center oven rack for 28-30 minutes, until slightly puffed and set.
- Cool the brownies completely (at least 6 hours or overnight) before cutting, if you want them to be set and slice cleanly when you cut them. You can speed up the cooling process by cooling them at room temperature for 1 hour, then refrigerating them for 1-2 hours.
- Lift the cooled brownies out of the pan by the parchment paper onto a cutting board to cut them into servings. If you like, sprinkle the top of the brownies with coarse finishing salt.
I don’t know what I did wrong with this one. I doubled the recipe and used a pyrex 9×13 pan. The brownies looked done after 30 minutes as the instructions described, and I let them cool on the counter for about 6 hours. When I went to slice them into squares, I realized the entire bottom brownie layer was uncooked except around the very edge pieces. I transferred the cut up sections back to a baking dish and “rebaked” which I know is a no-no, but wanted to at least make sure the eggs were thoroughly cooked for safety. They got runny and not very pretty, but were still delicious. I think in the future I would not double the recipe and would use a thermometer to check for doneness in the center. My family still thought they were great!
Lisa, I’m glad you liked them! I wonder if your oven runs a little low so they didn’t bake as quickly with a double batch.
That’s possible. It’s been several years since I’ve checked and calibrated it. Don’t get me wrong, we ate every morsel of my wonky looking bars. LOL
Hello, how high is your altitude for your baking? I’m also in Colorado and I am at almost 7000 feet. Most of my baking still comes out flat and not fluffy. Would you recommend that I decrease the baking soda more in your recipe?
Thank you
Darcy, here is some information from the FAQs on my site. You might need to decrease the baking soda a little more, but they might turn out as is, too.
I live in Denver, CO. I bake and test everything at high altitude (5,280 feet above sea level, which is why this is called the “mile high city”). Cookie baking, bread making and especially cake baking, can be affected by altitude. So if you live at a lower altitude or at sea level, you may need to make some minor adjustments to the flour, sugar, liquid and leavening agents. Here is an excellent article by King Arthur Baking with charts on how to convert a recipe from low altitude to high altitude, which you can simply reverse for converting from high altitude to low altitude. Another good resource is the Colorado State University Extension for high altitude food preparation.
https://www.kingarthurbaking.com/learn/resources/high-altitude-baking
https://extension.colostate.edu/topic-areas/nutrition-food-safety-health/high-altitude-food-preparation-p41/
Will your recipes only work at high altitude or can I make them if I live at sea level? This is the most frequent question I get from visitors to my site. If I’ve labeled a recipe as “high altitude” in the title, then it’s something that’s more affected by altitude than other bakes. For example, baked goods containing chemical leaveners, such as cakes, cupcakes, cookies, muffins, brownies, bar cookies and some breads are the most affected by high altitudes. Other recipes like ice cream, no bake cheesecake, cutout cookies (without leavening), buttercream, fruit crumbles, pies and tarts are affected the least, if at all.
So to answer your question, you may or may not need to make adjustments for sea level baking. For cakes and other baked goods, you will likely need to reduce the flour by several tablespoons and slightly increase the leavening for it to rise correctly at sea level or low altitude. However, I’ve had feedback from many people who make my recipes at sea level without adjusting them, and they’ve reported back that they’ve worked out great for them.