If you love peanut butter and simple baking, these peanut butter cookie bars are for you. Soft, chewy, and easy to make from scratch, they deliver the classic salty-sweet peanut butter flavor. Stir in chocolate chips or M&M’s for extra fun and texture.
These bars satisfy that craveable combination of salty and sweet. Peanut butter gives them both flavor and structure, while melted butter keeps them tender. I usually enjoy them plain, but chocolate chips, M&M’s or chopped nuts are great additions if you want a little extra.
Table of Contents
Why this recipe works
Melted butter combined with creamy peanut butter creates a dough that bakes up soft and chewy. The method is quick and forgiving, and the base is versatile—mix-ins like chocolate chips, M&M’s, or chopped nuts fold in easily to change the flavor and texture.
Ingredient notes
- Peanut butter: Use creamy no-stir peanut butter for the best texture. Avoid brands that separate with oil on top, which can make the bars greasy or crumbly.
- Butter: Unsalted butter is recommended since peanut butter already adds salt. Let melted butter cool slightly before mixing so it doesn’t affect the sugars or egg.
- Flour: All-purpose flour works well. A cup-for-cup gluten-free flour can be used as a substitute; avoid nut flours, which can make the bars too dense.
Recipe variations
Add 3/4 cup of mix-ins such as chocolate chips, M&M’s, Reese’s pieces, peanut butter chips, or chopped nuts. Fold them in by hand after the dough comes together so they stay evenly distributed.
If you prefer a finished look, spread a simple chocolate frosting over cooled bars. For a peanut-forward dessert, try using a peanut butter frosting on similar bars or brownies.
For a fruity version, make peanut butter and jelly bars using the same cookie dough base with a jam layer folded or swirled in.
How to make peanut butter cookie bars
- Whisk together the dry ingredients: flour, baking soda, and salt. Set aside.
- Combine melted (and slightly cooled) butter with creamy peanut butter until smooth. Add brown sugar and granulated sugar; beat until combined. Mix in the egg and vanilla until incorporated.
- Add the dry ingredients and mix just until combined. The dough will be soft and slightly crumbly; that’s normal. Fold in any mix-ins by hand.
- Press the dough into an 8×8-inch pan lined with parchment paper, smoothing the top. Bake at 350°F (175°C) for 20–22 minutes. Allow to cool completely before cutting for the best texture.
Expert tips
Don’t overbake. Remove the bars when the center still looks slightly underdone; they finish setting as they cool and will stay gooey and chewy. Let them cool completely in the pan before slicing so the bars hold together.
No kitchen scale? Grease the measuring cup before adding peanut butter so it slides out easily and you won’t need to scrape the cup.
Frequently Asked Questions
Bars can be crumbly if they’re overbaked or if there was too much flour. Use a kitchen scale or spoon and level the flour into the measuring cup instead of packing it.
Creamy no-stir peanut butter is best. Avoid separated, oily peanut butter for baking.
Yes. Double the recipe for a 9×13-inch pan and bake about 35 minutes, checking for doneness near the end of baking time.
Yes. You can mix by hand, though it will take more effort to fully combine the butters and sugars.
Related recipes
If you enjoy cookie bars, try these similar recipes for more inspiration.
Chocolate Chip Cookie Bars
Reese’s Pieces Peanut Butter Blondies
Peanut Butter Chocolate Bars with Shortbread Crust
Thick and Chewy Monster Cookie Bars
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Equipment
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1 8×8 metal baking pan
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Kitchen scale (recommended)
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Stand mixer or hand mixer (optional)
Ingredients
- 2 cups all-purpose flour (250 g)
- 1 teaspoon baking soda
- ½ teaspoon salt
- 6 Tablespoons unsalted butter, melted and slightly cooled (85 g)
- ½ cup creamy no-stir peanut butter (130 g)
- ¾ cup packed light brown sugar (150 g)
- ¼ cup granulated sugar (50 g)
- 1 teaspoon pure vanilla extract
- 1 large egg, room temperature
- ¾ cup chocolate chips, M&M’s, or nuts (optional, 140 g)
- 1-2 Tablespoons milk, if needed to adjust dough
Instructions
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Preheat oven to 350°F. Line an 8×8-inch metal baking pan with parchment paper and set aside.
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In a medium bowl, whisk together flour, baking soda, and salt. Set aside.
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In a mixer bowl or large mixing bowl, combine melted butter and peanut butter until smooth. Add brown sugar and granulated sugar and mix until combined. Add egg and vanilla and mix until incorporated.
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With the mixer on low, slowly add the dry ingredients and mix just until combined. If the dough seems too dry, add 1–2 tablespoons of milk. Fold in any mix-ins by hand.
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Press the dough evenly into the prepared pan and smooth the top.
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Bake for 20–22 minutes at 350°F. Cool in the pan for 10 minutes, then transfer to a rack to cool completely before cutting and serving.
Notes
Dry texture: Measure flour accurately—weight is best—or use the spoon-and-level method. If dough is dry, add 1–2 tablespoons milk.
Pan choice: A metal baking pan yields the best edge texture. Glass pans retain heat and can dry the edges.
Storage: Store bars in an airtight container at room temperature for up to 5 days. Freeze up to 1 month, wrapped well.