Peanut Butter Stuffed Chocolate Cookie Bars taste like peanut butter cups in cookie bar form! The peanut butter filling is sandwiched between soft chocolate cookie layers and baked to perfection. Peanut butter chocolate fans, this one's for you!

If you know me, you know my favourite candy by FAR are Reese's cups. They're so so delicious! Inside these cookie bars is an entire layer of peanut butter. It's like a giant Reese's.
This recipe is similar to my Peanut Butter Stuffed Chocolate Cookies, but in cookie bar form. Recently I've been really into making cookie bars, so I decided to recreate one of my favourite cookies into bars!
This recipe only requires simple ingredients we can find in our pantry. No fancy stuff! It comes together in a bowl with no electric mixer required. They're chocolate-y, full of peanut butter flavour, and studded with semi-sweet chocolate chips.
For more cookie bar recipes, try Halloween Candy Cookie Bars, Monster Cookie Bars, and Brown Butter Nutella Bars.
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Why this recipe works
Easy to make – No mixer required, one bowl, and simple ingredients you can find in your pantry.
Giant cookie – It tastes like a giant cookie and is the perfect recipe to make when you don’t want to roll out a dozen individual ones.
Peanut butter layer - There is a thick creamy layer of peanut butter inside. It tastes like a giant Reese's cup!
Ingredient Notes
Scroll to view a few ingredients notes. Full recipe and measurements can be found in the recipe card below.
Butter – I always use unsalted butter. This will be melted.
Brown sugar – I used golden yellow, but any kind of brown sugar works.
Cocoa powder - Using a dark cocoa powder brings that contrast and strong chocolate flavour. You can also use unsweetened cocoa powder.
Egg - Remove two hours before baking.
Peanut butter - Make sure you use creamy, and not natural.
Step by step Instructions
Here is how to make and bake these peanut butter chocolate cookie bars. You will need an 8×8 square pan lined with parchment paper, a large mixing bowl, a spatula, and a whisk.
Step 1 - Prep the pan. Preheat oven to 350°F. Line an 8×8-inch pan with parchment paper and spray with nonstick cooking spray. Set aside.
Step 2 - Mix the butter and sugars. Whisk the melted butter with brown sugar and white sugar. Add in eggs and vanilla.
Step 3 - Whisk the dry and wet ingredients together. Add in cocoa, flour, baking soda, and salt. A thick cookie dough batter will form. Add in the chocolate chips.
Step 4 - Make the peanut butter filling. Whisk together melted peanut butter, powdered sugar, vanilla, and milk. The mixture will be thick.
Step 5 - Layer the bars. Add half of the cookie dough to the bottom of your prepared pan. Place the filling on top, leaving an edge around. Top off with remaining cookie dough.
Step 6 - Bake the bars. Bake for 28-30 minutes. The bars will be ready when there's no shine on top. Allow to cool completely, slice, and enjoy!
Expert Baking Tips
Here are a few baking tips from my kitchen to yours
- Use dark cocoa powder if you want that dark brownie look and contrast. My go-to is this one.
- Allow the cookie bars to cool completely. The filling sets as it cools, so this is important!
- Make sure you use a creamy peanut butter, not natural. You can use any nut butter, as long as it is creamy.
FAQ
Can I use a 9x9 pan?
No! This recipe makes just enough for a thin layer of the cookie dough bars in an 8x8 pan. A 9x9 won't be completely covered. If you prefer a larger pan, you can double the entire recipe and use a 9×13-inch pan.
Can I use natural peanut butter?
No! You must use creamy. The consistency will be too runny if you use a natural nut butter.
Do I have to add chocolate chips?
No!
Can I use regular unsweetened cocoa powder?
Absolutely! I used the dark to get that contrast.
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Peanut Butter Chocolate Cookie Bars
Ingredients
- 1/2 cup butter melted
- 1/4 cup white sugar
- 1/3 cup light brown sugar
- 1 egg
- 1 tbsp vanilla
- 1/4 cup dark unsweetened cocoa powder
- 1 1/3 cups all-purpose flour
- 1/2 tsp baking soda
- 1/4 tsp salt
- 3/4 cups semi-sweet chocolate chips
Peanut Butter Layer
- 1 cup peanut butter creamy
- 1 cup powdered sugar
- 1 tsp vanilla
- 2 tbsp milk
Instructions
- Preheat oven to 350°F. Line an 8×8-inch pan with parchment paper and spray with nonstick cooking spray. Set aside.
- Melt the butter and then transfer it into a large bowl. Allow to cool for 10 minutes.1/2 cup butter
- Add white sugar and brown sugar and whisk until the mixture is smooth. Whisk in egg and vanilla extract.1/4 cup white sugar, 1/3 cup light brown sugar, 1 tbsp vanilla, 1 egg
- Fold in cocoa. Then slowly fold in the baking soda, salt, and flour until the batter is smooth and comes together. Don't overmix!1/4 cup dark unsweetened cocoa powder, 1 1/3 cups all-purpose flour, 1/2 tsp baking soda, 1/4 tsp salt
- Add in the chocolate chips and gently fold in a few times to incorporate them.3/4 cups semi-sweet chocolate chips
- Press half of the cookie dough in the bottom of the prepared pan. The layer will be thin, make sure the entire bottom is covered.
- Melt the peanut butter in the microwave or using a double boiler method. Transfer into a medium-sized bowl. Add in powdered sugar, milk, and vanilla. As you mix it, the mixture will turn very thick. Spread over the cookie layer, leaving a small border around the edges.1 cup peanut butter, 1 cup powdered sugar, 1 tsp vanilla, 2 tbsp milk
- Add the remaining cookie dough on top. Make sure to seal in all the edges!
- Bake for 30-35 minutes or until the top looks no longer glossy. Cool completely before slicing into bars. As the bars cool, they continue to bake, so this is important.
- Leave on the counter at room temperature for up to 3 days. Individually freeze for up to 2 months. Enjoy!
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