Peanut Butter Swirl Brownies

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August 4, 2025

These peanut butter swirl brownies are the BEST mash‑up of rich chocolate and creamy peanut butter! They’re ultra‑fudgy, swirled with a luscious peanut butter ribbon, and finished with melty chocolate chips for that bakery‑style look.

The best part? They’re EASY enough for a weeknight treat but impressive enough to WOW at parties. One bite, and you’ll see why this pan NEVER lasts more than a day in our house!

Helpful Tips & Variations

Use room‑temperature eggs. Cold eggs can make the batter seize up, giving you a denser texture. Room‑temperature eggs whip in smoothly, creating that perfect fudgy bite.
Don’t overmix after adding the flour. Once the dry ingredients go in, stir just until combined. Overmixing can lead to a tough brownie (and nobody wants that)!
Warm the peanut butter slightly. A quick 10–15 seconds in the microwave makes it silky and EASY to swirl for that marbled look.
Chill before slicing. If you want clean, bakery‑style cuts, let the brownies cool completely, then chill in the fridge for at least 30 minutes before slicing.
Switch up the nut butter. Almond butter or hazelnut spread can be swapped in for the peanut butter if you want a fun twist.
Add texture on top. Sprinkle chopped peanuts, pretzels, or even mini peanut butter cups over the batter before baking for a little crunch (and extra eye candy).

Ingredients

For the brownies:

1 cup unsalted butter, melted and slightly cooled
1 ¾ cups granulated sugar
3 large eggs, room temperature
2 teaspoons vanilla extract
1 cup all‑purpose flour
1 cup unsweetened cocoa powder
½ teaspoon salt
½ cup mini chocolate chips (plus extra for topping)

For the peanut butter swirl:

½ cup creamy peanut butter
3 tablespoons powdered sugar
2 tablespoons milk (just enough to loosen it for swirling)

How to Make Peanut Butter Swirl Brownies

1. Prep the pan. Preheat oven to 350°F (175°C). Line an 8×8‑inch baking pan with parchment paper, leaving an overhang for easy removal.

2. Mix the brownie batter. In a large bowl, whisk together melted butter and sugar until smooth. Add eggs and vanilla, whisking until glossy.

3. Add the dry ingredients. Sift in flour, cocoa powder, and salt. Fold gently until just combined. Stir in ½ cup mini chocolate chips.

4. Pour into pan. Spread batter evenly in the prepared pan.

5. Make the swirl. In a small bowl, mix peanut butter, powdered sugar, and milk until smooth. Drop spoonfuls of peanut butter mixture over brownie batter. Use a butter knife to gently swirl for that marbled look.

6. Top it off. Sprinkle extra mini chocolate chips over the top for that WOW factor!

7. Bake. Bake for 28–32 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs (not clean, that’s how you know they’re fudgy).

8. Cool and cut. Let brownies cool completely before lifting them out and slicing. For those perfect squares, chill in the fridge before cutting.

Proper Storage

Room temperature: Store in an airtight container for up to 3 days. They’ll stay soft and gooey without drying out.
Refrigerator: If you like a denser, chilled brownie (kind of like brownie fudge), store them in the fridge for up to 5 days. Just let them sit at room temp for a few minutes before eating so the peanut butter swirl softens.
Freezer: Wrap individual brownies in plastic wrap, then place them in a freezer‑safe bag or container. They freeze beautifully for up to 2 months. Thaw at room temperature or give them a quick zap in the microwave for a fresh‑baked taste.

We hope you LOVE these peanut butter swirl brownies as much as we do. They’re the kind of dessert that disappears fast (sometimes before they even cool). If you make a batch, we’d LOVE to hear how they turned out for you!