These peanut butter swirl brownies pair a fudgy cocoa base with ribbons of sweet peanut butter filling and chopped peanut butter cups.
The batter mixes in one bowl, and the swirl takes only a few minutes with a butter knife. Each square has chocolate, peanut butter, and a little crunch in every bite.
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Why This Peanut Butter Swirl Brownies Recipe Works
Melted chocolate plus cocoa gives a double dose of chocolate flavor, which stands up to the rich peanut butter. Brown sugar adds moisture and a slight caramel note.
The swirl mixture is sweetened with powdered sugar and softened with melted butter, so it spreads easily and stays creamy after baking.
Using only two thirds of the batter for the bottom layer leaves enough on top to cover the filling, which keeps the swirl from drying out.
Ingredients for Peanut Butter Swirl Brownies
- 4 ounces bittersweet chocolate, chopped
- 3/4 cup unsalted butter, cut into chunks
- 1/2 cup unsweetened cocoa powder
- 1 cup granulated sugar
- 1/2 cup brown sugar, packed
- 3 large eggs, room temperature
- 1 tablespoon pure vanilla extract
- 1/2 teaspoon instant espresso powder (optional)
- 3/4 cup all purpose flour
- 1/2 teaspoon kosher salt
- 3/4 cup chopped peanut butter cups, plus more for topping
- 3/4 cup peanut butter baking chips, plus more for topping
- 3 tablespoons unsalted butter, melted
- 3/4 cup creamy peanut butter
- 1/3 cup powdered sugar
- 1 teaspoon pure vanilla extract
Bittersweet chocolate. Melted into the batter, it gives a deep chocolate flavor and a glossy crumb.
Creamy peanut butter. Use a conventional creamy peanut butter. Natural styles separate and make the swirl oily.
Peanut butter cups. Chop them roughly so they stay in pieces inside the brownies.
Peanut butter baking chips. They add pockets of sweet peanut butter flavor on top of the batter.
Brown sugar. Packed brown sugar keeps the brownies moist and chewy.
How to Make Peanut Butter Swirl Brownies
1. Prepare the pan Heat the oven to 350 degrees F. Grease a 9×9 inch pan and line it with a parchment sling for easy lifting.
2. Melt the chocolate Melt the chocolate and butter in a microwave safe bowl at half power, stirring every 30 seconds until smooth.
3. Mix the brownie batter Whisk in the cocoa and both sugars, then stir in the eggs, vanilla, espresso powder, flour, and salt. Fold in the chopped peanut butter cups and baking chips.
4. Make the filling Stir the melted butter, peanut butter, powdered sugar, and vanilla together in a separate bowl until just combined.
5. Layer and swirl Spread two thirds of the batter into the pan, dollop the peanut butter mixture on top, and cover with the remaining batter. Drag a butter knife through to swirl gently.
6. Top and bake Scatter more chopped cups and chips on top. Bake for 30 to 35 minutes, until a toothpick shows a few moist crumbs.
7. Cool and cut Cool completely in the pan before slicing into 16 squares.
How to Serve Peanut Butter Swirl Brownies
Cut the brownies into small squares since they are rich, and serve them with cold milk or coffee. A scoop of vanilla ice cream beside gooey brownie pie makes a dessert plate for chocolate lovers. They also look great next to thick chocolate chip cookies and silky chocolate ganache for dipping, plus a glass of berry kefir smoothie on the side.
How to Store and Reheat Peanut Butter Swirl Brownies
Keep the brownies in an airtight container at room temperature for up to 4 days, or refrigerate for up to 1 week. Freeze wrapped squares for up to 3 months and thaw at room temperature. Let chilled squares sit for 15 minutes before serving so the peanut butter filling softens.
Tips and Variations for Peanut Butter Swirl Brownies
Use a parchment sling. It lets you lift the slab out and cut clean squares.
Do not overswirl. A few passes with a knife keep distinct ribbons.
Chop the candy. Smaller pieces spread more evenly through the batter.
Cool the chocolate. Let the melted chocolate cool a few minutes before adding the eggs.
Switch the nut butter. Almond or sunflower butter works in the filling for a different flavor.
Try other chips. Chocolate, white chocolate, or caramel chips also work.
Skip the raw batter. The batter contains raw eggs and raw flour, so only taste the baked brownies.
Store them safely. Refrigerate leftovers within two hours, using the Montana State University Extension egg fact sheet for egg handling basics.
Frequently Asked Questions About Peanut Butter Swirl Brownies
How do you swirl peanut butter swirl brownies?
Dollop the filling over the bottom layer, cover with the remaining batter, and drag a butter knife through in a figure eight motion.
Can I use natural peanut butter in peanut butter swirl brownies?
A conventional creamy peanut butter works well, because natural styles are too oily and can separate.
How long do peanut butter swirl brownies last?
They keep for 4 days at room temperature and 1 week in the refrigerator.
Can I make these gluten free?
Use a 1 to 1 gluten free baking flour blend in place of the flour, and check the labels on the chocolate.
What pan size should I use?
A 9×9 inch pan gives thick squares, and an 8×8 inch pan makes them even thicker with a longer bake.
Peanut Butter Swirl Brownies with Peanut Butter Cups
Equipment
- 9×9 inch baking pan
- Parchment paper
- microwave safe bowl
- Butter knife
- Wire rack
Ingredients
Main Ingredients
- 4 oz bittersweet chocolate chopped
- ¾ cup unsalted butter cut into chunks
- ½ cup unsweetened cocoa powder
- 1 cup granulated sugar
- ½ cup brown sugar packed
- 3 large eggs room temperature
- 1 tbsp pure vanilla extract
- ½ tsp instant espresso powder optional
- ¾ cup all purpose flour
- ½ tsp kosher salt
- ¾ cup chopped peanut butter cups plus more for topping
- ¾ cup peanut butter baking chips plus more for topping
- 3 tbsp unsalted butter melted, for the swirl
- ¾ cup creamy peanut butter conventional style, for the swirl
- ⅓ cup powdered sugar for the swirl
- 1 tsp pure vanilla extract for the swirl
Instructions
Cooking
- Prep the pan. Heat the oven to 350 degrees F, grease a 9×9 inch pan, and line it with a parchment sling.
- Melt the chocolate. Microwave the chocolate and butter at half power in 30 second pops, stirring until smooth.
- Make the batter. Whisk in the cocoa, both sugars, eggs, vanilla, espresso powder, flour, and salt, then fold in the peanut butter cups and chips.
- Make the swirl. Stir the melted butter, peanut butter, powdered sugar, and vanilla in a separate bowl until just combined.
- Layer and swirl. Spread two thirds of the batter in the pan, dollop on the filling, cover with the rest of the batter, and swirl once or twice with a butter knife. Top with more cups and chips.
- Bake. Bake for 30 to 35 minutes, until a toothpick shows a few moist crumbs, then cool for 1 hour before cutting.
