Desserts

Easy Fudgy Peanut Butter Swirl Brownies (From Scratch)

ByEric Jones posted onAugust 19, 2026August 22, 2026 Updated onAugust 22, 2026

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Few flavor combinations in the culinary world are as universally celebrated as rich chocolate and salty peanut butter. When you bring those two powerhouses together inside an intensely fudgy brownie—a batch of Easy Fudgy Peanut Butter Swirl Brownies is the end result!

Here are a few more desserts you might enjoy: Easy Fudgy Toffee Brownies, Chocolate Chip Cookie Ice Cream Sandwiches, No-Bake Oreo Cream Pie, Ooey Gooey Pineapple Butter Cake, and Easy Lemon Bars.

Only a few simple ingredients stand between you and this brownie creation. We melt unsalted butter with semisweet chocolate chips to build a glossy, decadent base, then whip granulated sugar, whole eggs, and pure vanilla extract to achieve that iconic crinkly crust.

We gently fold in unsweetened cocoa powder and just enough flour to ensure the brownies are dense, but not dry. Finally, we dollop and swirl creamy peanut butter right through the batter. It is decadent, perfectly salty-sweet, and simple enough to master any day.

overhead shot of fudgy peanut butter swirl brownies

Ingredients you’ll need to make Fudgy Peanut Butter Swirl Brownies:

Unsalted Butter: Delivers a rich flavor and ensures fudgy, melt-in-your-mouth brownies rather than a dry, cake-like texture.
Granulated Sugar: Sweetens the brownies and dissolves with the whipped eggs to create the signature shiny, crackly top crust.
Semisweet Chocolate Chips: Melting real chocolate with the butter introduces essential cocoa butter, giving the batter body, gloss, and a deeper chocolate flavor.
Eggs: Act as the primary binder, providing natural lift without making the brownies airy or cakey.
Vanilla Extract & Sea Salt: Vanilla enhances sweetness, while sea salt sharpens the chocolate and balances the peanut butter’s richness.
Unsweetened Cocoa Powder: Delivers a concentrated, punchy cocoa depth without adding extra butter or liquid.
All-Purpose Flour: Kept to a minimum proportion to ensure maximum chewiness and density.
Baking Soda: Provides a delicate tenderness along the edges without leavening the brownies into a cake.
Creamy Peanut Butter: Adds a roasted, salty-savory flavor and a creamy texture that cuts through the deep chocolate base.

How to make Fudgy Peanut Butter Swirl Brownies:

Prep the Oven and Pan. Preheat your oven to 325°F. Lightly coat an 8×8-inch baking pan with nonstick cooking spray. Line the bottom and sides with parchment paper, leaving an overhang on opposite sides for easy removal later.

Melt the Butter, Sugars, and Chocolate. In a small saucepan over medium heat, combine the unsalted butter and granulated sugar. Turn off the heat, then add the chocolate chips and stir until melted, smooth, and glossy. Add to a large bowl and set aside to cool slightly.

Whisk in the Eggs. Add the eggs and vanilla to the cooled chocolate mixture. Using a whisk, beat vigorously for 2 minutes until fully incorporated and glossy.

Fold in the Dry Ingredients. Using a rubber spatula or wooden spoon, fold the unsweetened cocoa powder into the bowl until fully incorporated. Add the all-purpose flour, sea salt, and baking soda. Gently fold the dry ingredients in just until no dry flour streaks remain. Do not overmix.

adding cocoa to the brownie's chocolate base

Pan and Swirl. Pour the thick brownie batter into the prepared baking pan and smooth the top evenly with your spatula (paid link). Warm the creamy peanut butter in the microwave for 10 to 15 seconds until slightly fluid. Drop generous spoonfuls of peanut butter across the batter. Use a butter knife, offset spatula (paid link), or toothpick to gently drag and swirl the peanut butter through the top layer of batter.

swirling peanut butter on top of the brownie batter

Bake. Bake for 35 to 40 minutes, or until a toothpick inserted into the center comes out with a few moist, fudgy crumbs (not wet batter).

Cool and Slice. Remove from the oven and let the brownies cool completely in the pan on a wire rack for at least 30 minutes. Lift out using the parchment overhang and slice into clean squares.

stack of three fudgy peanut butter brownies

Peanut Butter Swirl Brownies Tips

Brownies can fall into two basic categories: cakey and fudgy. Cakey brownies have a cake-like texture that is light, somewhat fluffy, and airy, while fudgy brownies are moist, dense, and gooey. I prefer a fudgy brownie, so this recipe has a higher fat-to-flour ratio. This means it has more chocolate and butter and less flour (and zero baking powder).
Once all ingredients are blended, your brownie batter should be smooth and thick. It should not be too loose.
Microwaving the peanut butter for 10–15 seconds makes it easier to swirl cleanly across the thick batter. I find that using the back edge of an offset spatula (paid link) or a butter knife works perfectly for creating a nice swirl.
Make broad, deliberate figure-eight motions with your knife. Over-mixing will blend the peanut butter directly into the batter rather than leaving distinct, beautiful ribbon swirls.
Store cooled brownies in an airtight container at room temperature for up to 4 days, or refrigerate for up to 1 week for an even denser, chewier texture.
Wrap individual sliced squares tightly in plastic wrap and store them in a freezer-safe bag for up to 3 months. Thaw at room temperature for 30 minutes before serving.

I’ll be honest—there aren’t too many desserts that blend peanut butter and chocolate that I won’t get excited about. So if you’re going to indulge, then brownies are probably high on your list. Who’s with me?

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