Fudgy Peanut Butter Swirl Brownies

Name: Fudgy Peanut Butter Swirl Brownies
Prep time: 20 min
Cook time: 32 min
Total time: 52 min
Yield: 16 servings
Cuisine: American
Ingredients: ½ cup (1 stick) (113 g) unsalted butter, cut into pieces; 4 oz (113 g) semisweet or bittersweet chocolate, finely chopped; ¾ cup (150 g) granulated sugar; ¼ cup, packed (55 g) light brown sugar; 2 (100 g) large eggs, at room temperature; 2 tsp (10 ml) pure vanilla extract; ½ cup (65 g) all-purpose flour, spooned into the cup and leveled; ¼ cup (22 g) unsweetened cocoa powder, sifted if lumpy; ½ tsp (3 g) fine salt; ½ cup (130 g) creamy peanut butter, regular (not natural-style); 3 tbsp (22 g) powdered sugar; 1 tbsp (15 ml) whole milk

From the MyKitchenBank Kitchen

Dense, fudgy chocolate brownies with a crackly top and ribbons of creamy peanut butter swirled through. Made in one bowl with pantry ingredients, they're rich, chewy and easy to cut into clean squares.

Prep: 20 min
Cook: 32 min
Wait: 2 hr 30 min
Total: 3 hr 22 min
Makes: 16 brownies (one 8-inch pan)

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Ingredients

16 servings

For the brownie batter
½ cup (1 stick) (113 g) unsalted butter, cut into pieces
4 oz (113 g) semisweet or bittersweet chocolate, finely chopped
¾ cup (150 g) granulated sugar
¼ cup, packed (55 g) light brown sugar
2 (100 g) large eggs, at room temperature
2 tsp (10 ml) pure vanilla extract
½ cup (65 g) all-purpose flour, spooned into the cup and leveled
¼ cup (22 g) unsweetened cocoa powder, sifted if lumpy
½ tsp (3 g) fine salt
For the peanut butter swirl
½ cup (130 g) creamy peanut butter, regular (not natural-style)
3 tbsp (22 g) powdered sugar
1 tbsp (15 ml) whole milk

Equipment (9)

8×8-inch (20×20 cm) square metal baking pan
Parchment paper
Medium saucepan or large microwave-safe bowl
Large mixing bowl and whisk
Rubber spatula
Small microwave-safe bowl
Butter knife or skewer for swirling
Wire rack
Sharp knife for cutting

Steps

Before you start

Take the eggs out 30 minutes ahead so they mix in smoothly.
Use regular creamy peanut butter (such as Skippy or Jif), not natural oil-separated style, so the swirl stays thick and holds its shape.
Plan on 2 hours of cooling plus 30 minutes of chilling; cutting warm brownies makes them gooey and messy.
Position an oven rack in the center and preheat the oven before you start mixing.

1
Prep the panOven 350°F / 175°C
- Position a rack in the center of the oven and heat to 350°F (175°C).
- Line an 8×8-inch (20×20 cm) metal pan with parchment, leaving an overhang on two opposite sides to use as handles.
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Ready when: Pan is lined with parchment smoothly pressed into the corners.
Tip: Lightly grease the pan first so the parchment sticks in place.
2
Melt butter and chocolate
- In a medium saucepan over low heat, melt the butter with the chopped chocolate, stirring constantly with a spatula, 3 to 4 minutes.
- Remove from the heat and keep stirring for 1 minute.
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Ready when: Mixture is completely smooth, glossy and no chocolate pieces remain.
Tip: Don't let it get hot or bubbling; scorched chocolate turns grainy.
3
Whisk in sugars
- Whisk both sugars into the warm chocolate mixture for 1 minute.
- Let it cool for 5 minutes so the eggs won't scramble.
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Ready when: Mixture feels warm, not hot, to the touch of the pan's side.
4
Add eggs and vanilla
- Whisk in the eggs one at a time, then the vanilla.
- Whisk vigorously for 1 full minute.
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Ready when: Batter looks thick, shiny and slightly lighter in color; this builds the crackly top.
5
Fold in dry ingredients
- Sift or sprinkle the flour, cocoa and salt over the batter.
- Fold with a spatula just until no dry streaks remain, about 15 strokes.
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Ready when: Batter is thick, glossy and uniformly dark.
Tip: Overmixing makes brownies cakey and tough.
6
Make the peanut butter swirl
- In a small microwave-safe bowl, stir the peanut butter, powdered sugar and milk together.
- Microwave 15 to 20 seconds, then stir until smooth and spreadable.
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Ready when: Mixture is smooth and spoonable, like thick frosting.
Tip: If it is runny, it will sink into the batter; let it sit 2 minutes to thicken.
7
Assemble and swirl
- Spread the brownie batter evenly into the pan.
- Drop spoonfuls of peanut butter mixture over the top, about 8 dollops.
- Drag a butter knife through the dollops in a figure-eight pattern, making 4 to 5 passes only.
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Ready when: Visible marbled ribbons of peanut butter across the surface.
Tip: Don't over-swirl, or the contrast disappears.
8
BakeOven 350°F / 175°C
- Bake at 350°F (175°C) for 30 to 34 minutes, rotating the pan after 18 minutes.
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Ready when: Edges are set and slightly pulling away from the pan; a toothpick in a chocolate area comes out with a few moist crumbs, not wet batter.
Tip: Overbaking is the main cause of dry brownies; start checking at 30 minutes.
9
Cool completely
- Set the pan on a wire rack and cool for 2 hours at room temperature.
- Then refrigerate 30 minutes for the cleanest cuts.
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Ready when: Center is firm to a light touch and no longer jiggles.
10
Slice and serve
- Lift the brownies out using the parchment overhang.
- With a sharp knife wiped clean between cuts, cut into a 4×4 grid of 16 squares.
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Ready when: Squares have clean, fudgy edges.
Tip: Run the knife under hot water and dry it between cuts.

Good to know

Tips

Whisk the eggs in vigorously for a full minute; this creates the shiny, crackly top.
Use a metal pan; glass bakes unevenly and often over-browns the edges.
For extra peanut flavor, sprinkle 1/4 cup chopped roasted peanuts over the top before baking.
Wipe the knife clean between each cut for neat squares.

Make ahead

Bake, cool and cut the brownies up to 2 days ahead. Store airtight at room temperature; they taste even fudgier on day two.

Storage & reheating

Room temperature in an airtight container up to 4 days. Refrigerate up to 1 week (bring to room temperature or microwave 8 to 10 seconds for a warm, gooey texture). Freeze, wrapped individually, up to 3 months; thaw overnight at room temperature.

Substitutions

creamy peanut butter → Chunky peanut butter. Adds crunch; the swirl will be a bit less smooth.
semisweet or bittersweet chocolate → Milk chocolate. Gives a sweeter, softer brownie; reduce the granulated sugar to 2/3 cup (135 g).
unsalted butter → Salted butter. Use it as is and reduce the added salt to 1/4 tsp.
light brown sugar → Granulated sugar. Use an equal amount; the brownies will be slightly less chewy.