If you’re a chocolate + peanut butter fan, these Peanut Butter Swirl Brownies are the dessert of your dreams. The base is a deeply chocolatey, Ghirardelli-inspired brownie that bakes up thick, dense, and fudgy—no chunks, no chips—just smooth, indulgent chocolate from a combination of rich cocoa powder and melted bittersweet baking chocolate.
To take things over the top, we swirl in a creamy peanut butter mixture that stays soft after baking. Each bite is the perfect blend of rich chocolate and salty-sweet peanut butter, and the marbled top makes them look as good as they taste.
Recipe Tips
For the best flavor I like to use Ghirardelli cocoa powder, but you can use any natural cocoa powder you prefer. High-quality chocolate makes a big difference here and really gives these brownies that rich, bakery-style taste. You can usually find both in the baking aisle at most grocery stores.
This recipe skips chocolate chunks and chips so the texture stays smooth and dense. All the chocolate flavor comes from the cocoa powder which keeps every bite rich and velvety. You can add chocolate chunks or chips if you want!
When it comes to swirling, less is more. Use a butter knife to make gentle figure-eight motions through the peanut butter and brownie batter. Overmixing will blend them too much and you’ll lose that pretty marbled look.
If you’re a fudgy brownie fan, pull them from the oven right at the 30–35 minute mark. For a more cake-like texture, give them an extra 5–8 minutes. The toothpick test is your friend—look for moist crumbs, not wet batter.
The peanut butter swirl
I originally planned to just spoon plain peanut butter onto the brownies and swirl it in, but once I thought about it, I realized I wanted something a little sweeter to balance the rich chocolate. I ended up mixing the peanut butter with a bit of powdered sugar and melted butter, which not only added sweetness but kept it soft and creamy even after baking. Melting the mixture in the microwave for about 10–15 seconds made it much easier to dollop and swirl into the batter—just warm enough to loosen it without making it runny.
Storage & Freezing
- Store in an airtight container at room temperature for up to 4 days.
- Freeze individually wrapped brownies for up to 3 months. Thaw at room temp before serving.
These Peanut Butter Swirl Brownies are pure comfort—smooth, chocolatey, and swirled with just enough peanut butter to keep every bite interesting. They’re simple to make but look like you spent hours in the kitchen. If you want more brownie recipes, click here!
Peanut Butter Swirl Brownies
Ingredients
For the brownies:
- 1 cup salted butter melted
- 2 tbsp vegetable oil
- 1 ¼ cups granulated sugar
- 1 cup light brown sugar packed
- 4 eggs room temperature
- 1 tsp vanilla extract
- ½ tsp salt
- 1 cup all-purpose flour
- 1 cup Ghirardelli cocoa powder you can use any natural cocoa powder
For the peanut butter swirl:
- ½ cup creamy peanut butter not natural
- 2 tbsp powdered sugar
- 1 tbsp melted butter
- ½ tsp vanilla extract
Instructions
For the brownies:
- Preheat oven to 350°F. Grease and line a 9×9-inch baking pan with parchment paper, leaving an overhang for easy removal. In a large bowl, whisk together melted butter, vegetable oil, granulated sugar, and brown sugar until glossy and well combined.
- Add eggs and vanillawhisk for 30 seconds, until slightly thickened and lighter in color. Sift flour, cocoa powder, and salt into the bowl. Gently fold with a spatula until no dry streaks remain.
- In a small bowl, mix peanut butter, powdered sugar, melted butter, vanilla, and salt until smooth. Microwave for 10–15 seconds to loosen slightly for easier swirling.
- Spread half the brownie batter into the prepared pan. Drop spoonfuls of half the peanut butter mixture over the batter. Top with the remaining batter and dollops peanut butter mixture on top, then use a butter knife to swirl for a marbled look.
- Bake for 30–35 minutes for fudgy brownies, or 5–8 minutes longer for a more cake-like texture. A toothpick should come out with moist crumbs but no wet batter. Cool in the pan for at least 30 minutes before lifting out and slicing into 12 squares.
It says “In a small bowl, mix peanut butter, powdered sugar, melted butter, vanilla, and salt until smooth.” But it doesn’t say how much salt to add to the peanut butter mixture. I made it without the salt and it worked fine, I just wanted to point this out.