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Peanut-Butter Swirl Brownies

Dollops of peanut butter filling are spooned onto brownie batter; pulling a knife back and forth through both results in a marbleized look.

  • Yield: Makes 9 large or 16 small squares
Peanut-Butter Swirl Brownies

Source: Martha Stewart Living Special Issues, 2005



  • 8 tablespoons (1 stick) unsalted butter, cut into small pieces, plus more for pan
  • 2 ounces good-quality unsweetened chocolate, coarsely chopped
  • 4 ounces good-quality semisweet chocolate, coarsely chopped
  • 2/3 cup all-purpose flour
  • 1/2 teaspoon baking powder
  • 1/4 teaspoon salt
  • 3/4 cup granulated sugar
  • 3 large eggs
  • 2 teaspoons pure vanilla extract


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


  1. Preheat oven to 325 degrees. Butter an 8-inch square baking pan and line with parchment, allowing a 2-inch overhang. Butter lining (not overhang).

  2. Make batter: Put butter and chocolates in a heatproof medium bowl set over a pan of simmering water; stir until melted. Let cool slightly. Whisk together flour, baking powder, and salt in a bowl.

  3. Whisk granulated sugar into chocolate mixture. Add eggs, and whisk until mixture is smooth. Stir in vanilla. Add flour mixture; stir until well incorporated.

  4. Make filling: Stir together butter, confectioners' sugar, peanut butter, salt, and vanilla in a bowl until smooth.

  5. Pour one-third of batter into prepared pan; spread evenly with a rubber spatula. Drop dollops of peanut butter filling (about 1 tablespoon each) on top of batter, spacing about 1 inch apart. Drizzle remaining batter on top, and gently spread to fill pan. Drop dollops of remaining filling on top. Gently swirl peanut butter filling into batter with a butter knife, running the knife lengthwise and crosswise through layers.

  6. Bake until a cake tester inserted into brownies (avoid center and edges) comes out with a few crumbs but is not wet, about 45 minutes. Let cool slightly in pan, about 15 minutes. Lift out; let cool completely on a wire rack before cutting into squares. Brownies can be stored in an airtight container at room temperature up to 3 days.

Cook's Note

To swirl brownies, work quickly so that batter and filling don't set. Use two large spoons to drop dollops of filling on the first layer of batter about one inch apart. Repeat with next layer of batter and remaining filling. Drag a butter knife back and forth through the layers with the tip touching the bottom of the pan.

Reviews (27)

  • Curlycupcake 2 Jan, 2014

    The taste of the brownies is good but they crumbled apart on me. I had to bake them 10 minutes longer because they weren't set after I had baked them for the amount of time the recipe called for. When I tried to cut the first brownie it crumbled and I thought it was just because it was the first. But then the next and next crumbled too. I wouldn't make this recipe again.

  • EloiseCS 1 Nov, 2013

    Personally (don't listen to the others) - this was simply amazing! It was slightly more cake-like compared to a normal chewy brownie, but I preferred that! I edited the recipe a tad too - I doubled the amount of Peanut Butter on top (but I love Peanut Butter), added some milk chop chips on top of the Peanut Butter as well - because I absolutely adore chocolate! I then also added a few spoonful's of Peanut Butter into the chocolate mixture whilst it was melting. They were simply delightful!

  • gross 12 Oct, 2013

    So disgusting. Don't bother wasting your ingredients. This is not a brownie.

  • tastytastie 27 Jun, 2013

    It would be nice if Martha took a basic writing class before uploading any more recipes. There should have been two separate ingredient lists: one for the brownies and the other for the topping. As it is now, it is almost impossible to follow. Spend a little less energy being pretentious and a little more being CLEAR. I am sure most bakers are primarily interested in yielding positive results as opposed to reading a fancy web site.

  • MrCheese 18 Dec, 2014

    If you took the time to slow down and read carefully then you wouldn't have an issue with this recipe.

  • ESPK 18 Jun, 2013

    I wanted to add to my below review that the peanut butter filling portion of this recipe was actually quite good despite the whole brownie not being the best.

  • ESPK 17 Jun, 2013

    Unfortunately, I wish I had read more of the reviews for this recipe prior to making the brownies. If you like "cakey" brownies, then this is the recipe for you because even if you cut back on the baking time, they're still cakey. This recipe is not worth the time or ingredients that are needed to make it. Furthermore, the recipe is incredibly unclear the way it's written as it pertains to what the measurements of the ingredients are specific to the batter and filling. Very disappointing...

  • PIE Lover 11 Mar, 2013

    These brownies are chewy and soft. One of the best combo with peanut butter and chocolate, I think.

  • Rebecca Su 5 Mar, 2013


  • Rachel g 16 Feb, 2013

    These brownies are, hands down, the BEST I EVER HAD. Anyone who's unsure of making these, just make 'em!

  • momof4boyz 1 Feb, 2013

    I was in a hurry, so I used Ghiradelli brownie mix and added the M S peanut butter swirl, had to bake an xtra few min, but it was a big hit, very moist and fudgy!
    cheater, I know ; )

  • Happy_Birthday_Dr_Seuss 31 Jan, 2013

    Peanut-Butter Swirl Brownies
    Russell's Thursday Dinner
    Nutritious and Delicious!

  • Krista Tracy 7 Nov, 2012

    Made this recipe for my daughter's birthday and it came out SO good! Not dry at all and the cook time was perfect. Will definitely make these again!

  • lisamaria 12 Aug, 2012

    Wow, these brownies were a HUGE disappointment!!! I found them to be very cakey and dry, and I did NOT overbake them. They were done at 35 mins. I even used Ghiradelli chocolate and that didn't make any difference. I tried two and I honestly am considering discarding them b/c they are not worth the calories! This recipe is going in the trash. Sorry, Martha.

  • mwilly 10 Aug, 2012

    I really did not like this recipe, as others said- way too rich and too cakey. I prefer a gooey moist brownie. bleh.

  • ChristineSF 1 Aug, 2010

    I found these brownies to be very cakey, which is not my preference. If you prefer fudgy brownies, I would recommend using a different recipe for the batter.

  • acase 14 May, 2010

    These brownies are great- although the time is way too high. As another person commented, I would check the brownies at 35 minutes. They will probably be done. Unfortunately mine were a little charred by the full 45 minutes. Still yummy though with all of the corners cut off!

  • cheftash 16 Dec, 2009

    Does anyone know if this was a recipe in Martha's magazine from the around roughly December 2005? I've been looking for the recipe for ages!

  • ozburnmso 26 Jul, 2009

    I was too lazy to make the I used a box mix but made the filling as directed above and now every time I'm invited to the neighbor's for Sunday night dinner - if I don't have these brownies with me...they won't let me in!

  • Shorty01 24 May, 2009

    I made this exactly per recipe and it was delicious! My baking time was slightly reduced though, only 35-40 mins. Will definately make again.

  • rose20 21 May, 2009

    They were very good, but I just melted chocolate chips for the chocolate and it came out good. Had to increase the baking time though.

  • kell_rae 18 Nov, 2008

    I made this recipe out of "Martha Stewart's Cookies" cookbook. In that recipe, the 2 tsp of vanilla is, indeed, in with the batter part of the recipe while the 1/2 tsp is in with the filling. This recipe is rich, but delicious! My family was raving about these brownies. I am now online to send the recipe to a friend!

  • lovesbaking 26 Aug, 2008

    Something seemed to clash, the taste in this brownie. The chocolate made it to sweet or something. Next time i might use 3 ounces semisweet and 3 ounces milk chocolate...I also had to add 5-10 minutes onto the baking time.

  • baileyboy 5 Feb, 2008

    2 tsp. vanilla for the batter, and 1/2 tsp. for the filling

  • baileyboy 5 Feb, 2008

    re: vanilla issue, I would assume 2 tsp. vanilla extract for the batter,

  • janetrichards 11 Jan, 2008

    Need clarification. How much vanilla in batter? How much vanilla in filling?

  • robyn07 25 Dec, 2007

    The brownies were very good. They were VERY rich though and needed a bit longer in the oven about 5-10 minutes longer. If you don't mind having very rich brownies, they are perfect.

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