Peanut butter cookie bars are a classic peanut butter cookie in bar form. Tender and chewy on the inside, they have a slight crisp and golden brown color on the edges. Try them with a scoop of vanilla ice cream!
Why You'll Love This Peanut Butter Cookie Bars Recipe
- Delicious flavor: If you're a peanut butter lover, this will quickly become one of your favorite recipes.
- Easy dessert recipe: We love easy recipes around here. This recipe is done in a few simple steps, combining the wet ingredients with the dry ingredients, baking, and enjoying.
Speaking of easy desserts, we have no shortage of delicious bars to try if you're not feeling like baking batches of cookies.
Grab These Ingredients
Here are the simple ingredients for this easy peanut butter bars recipe. Most are pantry staples and easy (and affordable) to find in grocery stores. Jump down to the recipe card for exact measurements.
- All-purpose Flour: If you're substituting with gluten-free, use a 1:1 flour, like Bob’s Red Mill 1:1 Baking Flour. Spoon it into the measuring cup and level it off.
- Baking soda: Acts as a leaven. Be sure to check the expiration date on it!
- Cornstarch: for an extra chewy texture!
- Kosher salt: To balance out the sweetness!
- Unsalted butter: For a plant-based butter option, we love and always use Myokos. You can find it in any local grocery store.
- Creamy no-stir peanut butter: You'll want to use creamy peanut butter (not drippy with oil.)
- Light brown sugar: You can also use dark brown sugar, but it will change the flavor slightly.
- Granulated sugar: White sugar, organic cane sugar, or coconut sugar and any of its substitutes are all options.
- Vanilla extract: Grab a quality, pure vanilla extract.
- Egg: Cold eggs can chill the butter in the cookie dough (when it’s supposed to be melted), which impacts the final texture of the bars.
- Milk: Use any kind like skim milk, whole milk, or almond milk.
- Peanut butter chips: We used Reese’s Pieces, but white chocolate chips, butterscotch chips, or chocolate chips work as well.
Want to make peanut butter chocolate chip bars? Swap the peanut butter chips for regular chocolate chips!
How to Make These Easy Peanut Butter Cookie Bars
The full printable recipe is below, but let’s walk through the steps with some photos and a video so you have a clear idea of what to expect. This peanut butter cookie bars recipe is really easy and these step-by-step instructions will make sure they turn out every time.
Dry ingredients: Whisk the flour, baking soda, cornstarch, and salt together in a large mixing bowl.
Wet ingredients: In a medium bowl, whisk the melted butter, brown sugar, and granulated sugar together until no brown sugar lumps remain and the mixture is smooth. Whisk in the vanilla, egg, egg yolk, and then the milk. The mixture will be thick.
Combine: Pour the wet ingredients into the dry ingredients and use a rubber spatula to mix together until combined. The dough will be very soft and thick. Fold in the peanut butter chips. You don't need a stand mixer or electric mixer for this recipe, but you can use one if you prefer.
Tip: use regular chocolate chips or dark chocolate chips for peanut butter chocolate chip cookie bars! You could even drizzle melted chocolate on top of the bars.
Bake: Transfer the dough to the baking dish and press it into all four corners of the pan. Bake for 32-35 minutes or until lightly browned on the sides. Insert a toothpick into the center of the bars to test for doneness.
Serve: Allow the bars to cool in the pan set on a wire rack for at least an hour. Use the parchment paper to remove the bars from the pan. Cut and serve.
Video: Watch How to Make Peanut Butter Cookie Bars
There could be a number of reasons that your cookie bars turn out dry. Be careful not to overmix or overbake the bars, to use enough fat, and not to overdo it on the flour.
Excessive peanut butter can make the cookie dough too soft and sticky, resulting in flat cookies. It can also make the cookies overly greasy, but can also make them dry and crumbly. Be sure to follow the recipe's measurements to avoid these issues.
If you expect to finish the cookies within a few days, you can store them at room temperature in an airtight container. If you want to keep the cookies for more than a few days, you can store them in the refrigerator for up to a week.
Freezing and Storing Tips
To store: Store in an airtight container at room temperature for up to a week. You can make the cookie dough and chill it in the refrigerator for up to 3 days.
Freeze: Freeze the cookie dough for up to 3 months. After freezing, allow the dough to come to room temperature and continue baking. Baked cookie bars freeze well wrapped in plastic wrap for up to 3 months. Thaw peanut butter cookie bars overnight in the refrigerator and bring them to room temperature before serving.
More Peanut Butter Treats
Our gluten-free peanut butter blossoms have a gluten-free twist and are always a hit. For the classic version, try these peanut butter blossoms. Almond flour peanut butter cookies have the most intense peanut butter flavor.
Next time you need a gluten-free cookie recipe, reach for these chewy flourless peanut butter cookies or flourless monster cookies.
Peanut Butter Cookie Bars
- 2 ¼ cups (281 g) all-purpose flour spooned and leveled (Note 2 Gluten-Free)
- 1 teaspoon baking soda
- 1 ½ teaspoons cornstarch
- ½ teaspoon kosher salt
- 6 Tablespoons (85g) unsalted butter melted and slightly cooled (Note 3. Dairy-Free)
- ⅔ cup (173g) creamy no-stir peanut butter
- ¾ cup (150g) packed light brown sugar
- ¼ cup (50g) granulated sugar
- 1 teaspoon pure vanilla extract
- 1 large egg + 1 egg yolk room temperature (Note 4)
- 2 Tablespoons milk any kind
- 1 cup peanut butter chips we used Reese’s chips
- 8x8-inch square baking pan (Note 1)
- Preheat oven to 350°F. Line a square 8x8-inch pan with parchment paper, leaving an overhang on all sides to easily lift the bars out of the pan when cool.
- Whisk the flour, baking soda, cornstarch, and salt together in a large bowl.
- In a medium bowl, whisk the melted butter, peanut butter, brown sugar, and granulated sugar together until no brown sugar lumps remain and the mixture is smooth. Whisk in the vanilla, egg, egg yolk, and then the milk. The mixture will be thick.
- Pour the wet ingredients into the dry ingredients and use a rubber spatula to mix together until combined. The dough will be very soft and thick. Fold in the peanut butter chips. The chips may not stick to the dough because of the melted butter, but do your best to evenly distribute them into the dough.
- Transfer the dough to the prepared pan and press it into all four corners of the pan, smoothing out the top into an even layer.
- Bake for 32-35 minutes or until lightly browned on the sides. Insert a toothpick into the center of the bars to test for doneness. If it comes out clean, the bars are done. Start checking for doneness around 30 minutes as every oven and baking pan varies and can affect the cook time.
- Allow the bars to cool in the pan set on a wire rack for at least an hour. Use the parchment paper to remove the bars from the pan. Cut into 16 squares and serve. Store in an airtight container at room temperature for up to a week.