Classic Salted Peanut Butter Swirl Brownies

Quick Recipe Version (TL;DR)

• Yield: 16 brownies
• Prep Time: 25 minutes
• Cook Time: 30 minutes
• Total Time: 1 hour 55 minutes (including cooling)

Quick Ingredients

• 1 cup (226 g) unsalted butter
• 8 oz (225 g) semisweet or bittersweet chocolate, chopped
• 1 1/2 cups (300 g) granulated sugar
• 1/2 cup (100 g) light brown sugar
• 4 large eggs, room temperature
• 2 tsp vanilla extract (plus 1 tsp for swirl)
• 1 cup (125 g) all-purpose flour
• 1/3 cup (35 g) unsweetened cocoa powder
• 3/4 cup (190 g) creamy peanut butter
• 1/3 cup (40 g) powdered sugar
• 2 tbsp unsalted butter, melted (for swirl)
• 2–3 tbsp milk or heavy cream
• 3/4 tsp fine salt total, plus flaky salt for topping

Do This

• 1. Heat oven to 350°F (175°C). Line a 9×13-inch pan with parchment and lightly grease.
• 2. For swirl: Whisk peanut butter, powdered sugar, 2 tbsp melted butter, 1 tsp vanilla, 1/4 tsp salt, and 2–3 tbsp milk until smooth and pourable.
• 3. For brownie batter: Melt 1 cup butter with chopped chocolate until smooth. Cool 5 minutes.
• 4. Whisk in sugars, then eggs and 2 tsp vanilla until thick and glossy. Sift in flour, cocoa, and 1/2 tsp salt; fold just until combined.
• 5. Spread batter in pan. Dollop peanut butter mixture over top and drag a knife through to create swirls.
• 6. Bake 28–32 minutes, until edges are set and center is just slightly fudgy.
• 7. Cool completely, sprinkle with flaky salt, slice into 16 squares, and serve.

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Why You’ll Love This Recipe

• Rich, fudgy chocolate brownies marbled with creamy, salty-sweet peanut butter ribbons in every bite.
• Uses simple pantry ingredients but looks beautifully impressive thanks to the dramatic swirl.
• Perfect texture: shiny crackly top, chewy edges, and a dense, moist center.
• Great for parties, bake sales, or freezing ahead for last-minute treats.

Grocery List

• Produce: None
• Dairy: Unsalted butter, milk or heavy cream
• Pantry: Semisweet or bittersweet chocolate, granulated sugar, light brown sugar, powdered sugar, all-purpose flour, unsweetened cocoa powder, creamy peanut butter, vanilla extract, fine salt, flaky sea salt (optional)

Full Ingredients

For the Fudgy Brownie Batter

• 1 cup (2 sticks / 226 g) unsalted butter, cut into pieces
• 8 oz (225 g) semisweet or bittersweet chocolate (60–70% cacao), chopped
• 1 1/2 cups (300 g) granulated sugar
• 1/2 cup (100 g) packed light brown sugar
• 4 large eggs, at room temperature
• 2 tsp pure vanilla extract
• 1 cup (125 g) all-purpose flour, spooned and leveled
• 1/3 cup (35 g) unsweetened cocoa powder
• 1/2 tsp fine sea salt

For the Salted Peanut Butter Swirl

• 3/4 cup (190 g) creamy peanut butter (no-stir style works best)
• 1/3 cup (40 g) powdered sugar, sifted
• 2 tbsp unsalted butter, melted and slightly cooled
• 2–3 tbsp milk or heavy cream, as needed for a pourable consistency
• 1 tsp pure vanilla extract
• 1/4 tsp fine sea salt

Optional Topping

• Flaky sea salt, for sprinkling after baking
• 2–3 tbsp chopped roasted peanuts, for extra crunch

Step-by-Step Instructions

Step 1: Prep the pan and oven

Preheat your oven to 350°F (175°C) with a rack in the center position. Lightly grease a 9×13-inch metal baking pan with butter or nonstick spray. Line the bottom and long sides with a sheet of parchment paper, leaving some overhang on the long sides to create a sling. This makes it easy to lift the brownies out later for clean slicing. Lightly grease the parchment as well.

Step 2: Make the salted peanut butter swirl

In a medium bowl, combine the 3/4 cup creamy peanut butter, 1/3 cup powdered sugar, 2 tbsp melted butter, 1 tsp vanilla, and 1/4 tsp fine salt. Whisk until smooth and thick. Add 2 tbsp milk or heavy cream and whisk again. The mixture should be creamy and ribbons should fall easily off the whisk. If it still seems too thick to dollop and swirl, add up to 1 additional tablespoon milk or cream, 1 teaspoon at a time, whisking after each addition. Set aside while you make the brownie batter.

Step 3: Melt the butter and chocolate

In a large heatproof bowl, combine the 1 cup unsalted butter and 8 oz chopped chocolate. Melt them together using either a double boiler or the microwave. For the microwave, heat in 20–30 second bursts, stirring thoroughly between each, until the mixture is completely smooth and glossy. Do not overheat; stop as soon as the last bits of chocolate melt from residual heat. Let this mixture cool for about 5 minutes so it is warm but not hot to the touch. This helps prevent scrambling the eggs.

Step 4: Build the brownie batter

Whisk the granulated sugar (1 1/2 cups) and light brown sugar (1/2 cup) into the melted chocolate mixture until fully combined and slightly thick. Add the 4 room-temperature eggs and 2 tsp vanilla. Whisk vigorously for about 45–60 seconds until the batter looks well combined, slightly lighter in color, and glossy. This brief whisking step adds a shiny, crackly top to your brownies.

In a separate bowl, whisk together the flour (1 cup), cocoa powder (1/3 cup), and fine salt (1/2 tsp) until no streaks remain. Sift if your cocoa is lumpy. Sprinkle the dry ingredients over the wet mixture and gently fold with a spatula just until no dry pockets remain. Do not overmix or you may lose the fudgy texture.

Step 5: Assemble the pan and swirl the peanut butter

Scrape the brownie batter into the prepared pan and spread it into an even layer, pushing it into the corners and smoothing the surface. Give the pan a gentle tap on the counter to release any large air bubbles.

Using a spoon, drop the peanut butter mixture over the brownie batter in evenly spaced dollops, leaving some brownie batter showing between each spoonful. Aim for 12–16 dollops across the surface.

Take a thin knife or skewer and gently drag it through the batter in long, looping motions to create marbled swirls. Try not to overwork it; you want visible chocolate and peanut butter ribbons rather than fully blending them together. Swirl all the way to the edges so each piece gets some peanut butter.

Step 6: Bake to fudgy perfection

Place the pan in the preheated oven and bake for 28–32 minutes. Baking times vary by oven, so start checking at 28 minutes. The edges should be set and slightly pulling away from the sides of the pan, and the center should look just set but still a bit soft and shiny. A toothpick inserted into a chocolate-only area near the center should come out with a few moist, fudgy crumbs, but not wet batter.

If using, immediately sprinkle a pinch or two of flaky sea salt over the hot brownies as soon as they come out of the oven. This will stick better while the top is still warm.

Step 7: Cool, slice, and serve

Let the brownies cool in the pan on a wire rack for at least 1 hour, or until they are just slightly warm or at room temperature. Cooling allows the fudgy center to set and makes slicing much cleaner. Once cool, use the parchment sling to lift the entire slab out of the pan onto a cutting board.

For neat squares, wipe your knife clean between cuts and use a gentle sawing motion. Cut into 16 pieces (4 by 4 grid) for generous brownies, or smaller squares if you prefer. Garnish with chopped roasted peanuts on top if desired. Serve as is, or warm slightly and top with a scoop of vanilla ice cream for an extra-indulgent dessert.

Pro Tips

• Use room-temperature eggs. Cold eggs can cause the chocolate mixture to seize slightly and make the batter harder to mix; room-temperature eggs blend more smoothly.
• Do not overbake. The brownies will continue to set as they cool. Pull them when the center is just barely set for the best fudgy texture.
• Swirl gently. For bold, distinct ribbons of peanut butter, drag the knife slowly and only a few times in each direction. Over-swirling leads to a uniform, less dramatic look.
• Use no-stir peanut butter. Natural peanut butters that separate can be too oily or too stiff; a smooth, commercial-style peanut butter gives the most reliable swirl.
• Chill for ultra-clean cuts. If you need picture-perfect squares, chill the cooled brownies in the fridge for 45–60 minutes, then slice with a warm, sharp knife.

Variations

• Extra crunchy. Stir 1/2 cup chopped roasted peanuts or chocolate chips into the brownie batter before spreading it in the pan for added texture.
• Dark chocolate lovers. Use 70% cacao chocolate and Dutch-processed cocoa for a deeper, more intense chocolate flavor and slightly less sweetness.
• Swirl sampler. Replace half of the peanut butter swirl mixture with Nutella or another nut butter and alternate dollops for a mixed-nut marbled pan.

Storage & Make-Ahead

Store cooled brownies in an airtight container at room temperature for up to 3 days. For longer storage, refrigerate them for up to 5 days; let them come to room temperature or warm briefly before serving for the best texture. To freeze, wrap individual brownies tightly in plastic wrap, then place them in a freezer bag or airtight container and freeze for up to 2 months. Thaw at room temperature or gently warm in a low oven. You can also prepare the peanut butter swirl up to 2 days in advance and store it covered in the refrigerator; bring to room temperature and stir until smooth before using.

Nutrition (per serving)

Approximate values for one of 16 brownies: Calories: 320, Total Fat: 21 g, Saturated Fat: 11 g, Carbohydrates: 31 g, Sugar: 23 g, Protein: 6 g, Fiber: 2 g, Sodium: 150 mg. These values are estimates and will vary based on specific brands and any variations you use.