Love and Olive Oil

Peanut Butter Swirl Brownies

Peanut Butter Swirl Brownies

It doesn’t take much to make me happy. A good brownie, for instance. I could eat brownies all day long and be perfectly content.

That said, boring brownies are for the birds. I like my brownies dressed up and ready to party. Whether filled, frosted, layered, or swirled, a brownie can be so much more than just a plain brown square.

Like, for instance, a dense chocolate wedge swirled with sweet peanut butter filling, permeating all the cracks and crevices like a peanut butter earthquake. Indeed, these peanut butter swirl brownies are a sight to be seen. And promptly eaten.

Peanut Butter Swirl Brownies

A word of warning if you decide to be fancy and bake your brownies in a round cake pan – unless you can figure out how to line the sides of said pan with parchment as well as the bottom, they will be tough to remove. Or, should I say, remove in one piece. They wedge themselves into the pan like a kid at Disneyworld, and no amount of coercion will convince them to come out early. I got them out eventually though, kicking and screaming, otherwise these photos might have looked quite a bit different.

As in, angry brownie splatters on the walls different.

Peanut Butter Swirl Brownies

I tried a slightly different brownie recipe than my usual this time, using a cocoa powder, vegetable oil, and boiling water base in place of my usual butter and melted chocolate. While I did love the texture (they’re pretty much spot on what you’d expect from a box brownie mix – both fudgy and chewy), I missed the rich flavor of the butter. Without the peanut butter swirl, I think these brownies may have been deemed a fail, as they were fairly flat and one-dimensional in flavor. Luckily, with these brownies it’s all about the peanut butter, so you wouldn’t really have known the difference if I hadn’t mentioned it. That said, feel free to substitute your own favorite brownie recipe in its place.

Peanut Butter Swirl Brownies

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For Brownie Base:

  • 1/3 cup dark or dutch-processed cocoa powder
  • 1/4 teaspoon baking soda
  • 1/3 cup vegetable oil, divided
  • 1/4 cup boiling water
  • 1 cup granulated sugar
  • 1 egg
  • 2/3 cup all-purpose flour
  • 1/2 teaspoon vanilla extract
  • 1/4 teaspoon salt

For Peanut Butter Swirl:

  • 3 tablespoons unsalted butter, melted
  • 1/2 cup smooth peanut butter
  • 1/3 cup confectioners’ sugar
  • 1/4 teaspoon salt
  • 1/2 teaspoon vanilla extract


  1. Preheat oven to 350 degrees F. Line an 8-by-8-inch square or round baking pan with parchment paper; butter parchment.
  2. In a large bowl, sift together the cocoa powder and baking soda. Add boiling water and half of vegetable oil and stir until mixture forms a thick paste. Mix in the sugar, egg, and remaining oil. Finally, add the flour, vanilla, and salt and fold until flour is just incorporated, taking care not to overmix.
  3. For the peanut butter swirl, combine peanut butter, butter, and vanilla in a bowl and stir until smooth. Add the confectioner’s sugar and salt and stir until smooth.
  4. Pour chocolate batter into prepared pan, then drop dollops of peanut butter filling on top. Use a butter knife to gently swirl the peanut butter into the batter. Since the peanut butter mixture is quite thick this won’t be perfect, just run your knife through it a few times and let it be.
  5. Bake for 35 to 40 minutes, or until a toothpick inserted into the center comes out clean. Transfer to a wire rack to cool to room temperature. For best results, refrigerate brownies a few hours or overnight before serving.

Adapted from All Recipes and Martha Stewart via The Baker Chick.

All images and text © / Love & Olive Oil

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  1. I meant “peanut butter” mixture.  

  2. Just made these a couple of nights ago. Oh my.  Using a dark cocoa makes these brownies perfect.  I added a bit more salt to the isn’t butter mixture.  My husband commented on how he liked the contrast.  Thank you for sharing this recipe.  A new favorite!

  3. A very nice thing I liked about this recipe is that it did not require “chips” such as peanut butter chips or chocolate chips. I usually have peanut butter and cocoa in my cabinet, and not chips. Thank you for such a basic recipe; I like simple:)

  4. These are delicious. I made this recipe but added about 2-3 more Tablespoons of flour because I was afraid they would be too chewy/gooey and they were still very nice and soft. The other alteration I made was, I substituted olive oil for vegetable oil, because I was out and the brownies were still wonderful. Rather than dropping the peanut butter mix with a spoon, I just kind of crumbled it with my hands and dropped it onto the brownie mixture.

  5. Drooling over this, yum! This is so perfect for me :)

  6. Do you think this would survive getting mailed for a few days  in an airtight box?

  7. I love this recipe.. mainly because it’s not crazy fattening.  Plus cocoa and peanut butter, so good for you.  I’m gonna bake these after the holidays and bookmark it for my healthy recipes.  :-)

  8. These look amazing. Chocolate and peanut butter is my boyfriends favorite dessert combo, must try these out on him :)

  9. Mmmmm…yum!! Love chocolate + peanut butter! These look fabulous! :)

  10. My husband is obsessed with warm brownies covered in cold vanilla ice cream and any combination of peanut butter and chocolate. These are going to make him unbelievably happy!

  11. I definitely need butter in my brownies, especially if they are plain brownies without any distractions. But you know I’m all over anything with peanut butter!

  12. I am not a fan of brownies…unless they look like THIS! Omg yes! Or those peppermint ones you made last year?? Yeah, that too

  13. You had me at fudgy and chewy. Best descriptions for good brownies. Putting peanut butter and chocolate together is always delicious and these look amazing! I love the idea of baking brownies in a round pan, even if they come out kicking and screaming ;)

  14. I would eat these even if I made them in a square pan, and just had to dig ’em out with my hands, I mean…a spoon. Right.
    I guess the wedge is a little more civilized though. These look to die for!

  15. can i use olive oil in this? or should i use something “lighter” ?

    • *maybe* light olive oil would work. Regular I think would be too strong a flavor. You could probably use coconut oil too!

    • I actually used “pure olive oil” and could not notice a difference. I did add about 2 extra tablespoons of flour for fear of it being gooey and they were still nice and soft.

  16. Peanut butter earthquake? Sign me up! And you know what? Even if disaster had struck with the brownie removal, I totally would have eaten these off the walls.

  17. not only do these look gorgeous, but I love the twist on traditional brownie slices – really gives it that extra “oomp”!! delish ;)

  18. Totally agree with everyone else–the wedge look is awesome!  As you mentioned though, I can imagine how difficult they are to remove from the pan–oh well.  Brownies are still brownies :)  I would eat them in whatever shape they came in.   

  19. Brownies that have peanut butter and are cut in to pie slices. I’ll take two please!

  20. Yummy! Have you tried Martha Wrap? It’s parchment on one side and foil on the other. So it holds a crease really well (just like regular aluminum foil). You might be able to use it to push and fold it into a round pan – sort of like working a pie crust!

  21. Obviously this one is a keeper! What a great addition to a holiday brunch! And serving them in pie wedges is a pretty change from squares, thank you so much!

  22. These look amazing! I love the wedge look! They look fudgy and delicious…and the peanut butter is an obvious “OMG.”

  23. HaaHaa, ‘wedged in like a kid at Disney World.’  too funny. The triangles sure are pretty tho ;}
    Nothing for the birds here! PB and chocolate are a marriage made in heaven!

  24. Party brownies – just my kind of thing! These look wonderful – love the swirls.

  25. I seriously cannot feel my torso right now.

  26. I love the look of the wedges of brownies (I think you actually must have done a good job getting them out of the pan because they look great!)  The peanut butter swirls look soo good.  I love chocolate and PB!

  27. I love the way you sliced these! They look fabulous!

  28. chocolate and peanut butter are always a perfect match! these brownies look so good!

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