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Rich and moist peanut butter cake topped with marshmallow frosting and peanut butter cups. It’s like biting into a fluffernutter sandwich, but better!

slice of peanut butter cake topped with marshmallow frosting and chopped peanut butter cups on a white plate with a fork

What is a Fluffernutter, you ask?

A fluffernutter is a peanut butter + marshmallow creme sandwich. My older sister Sarah loved them when we were growing up! The term fluffernutter can also describe desserts combining the tastes of peanut butter and marshmallow. And did you know? The Fluffernutter is the official sandwich of Massachusetts. They sure know what they’re doing up there!

peanut butter cake topped with marshmallow frosting and chopped peanut butter cups on a white cake stand

I had leftover Fluff (marshmallow creme) from making my S’mores Cookie Bars (must make!). I brainstormed for a minute and decided to use the rest of the XXL jar for frosting. A quick marshmallow frosting to pair with a super-moist, dangerously good peanut butter cake.

The peanut butter cake is the same batter I use for my super-moist, super peanut buttery Peanut Butter Cupcakes. This is my go-to peanut butter cupcake. It’s not made with white sugar – all brown sugar, baby. The brown sugar and the eggs are why it is so darn moist!

I find that many peanut butter cupcakes and peanut butter cake recipes lack flavor. They tend to have a dry texture and not nearly enough peanut butter taste. My peanut butter cake and cupcake recipe is the complete opposite. It’s like biting into pure peanut butter.

The best part? The peanut butter cake is so easy to make!

peanut butter cake topped with marshmallow frosting on a white cake stand

Doesn’t the frosting look like a cloud? So good. Creamy marshmallow sitting atop a moist peanut butter cake. Fluffernutter at its finest.

slice of peanut butter cake topped with marshmallow frosting and chopped peanut butter cups on a white plate

I spread the frosting on the cake with a knife. Nothing fancy. I opted out of frosting the sides of the cake because it is SO much easier to just frost the top. Save yourself the time. Depending on how thick you slather the frosting onto the cake, you may have leftovers.

Reese’s Peanut Butter Cups are the decor of choice for the cake. Because… why not? Chop up 8 full size Reese’s Cups and sprinkle around the edges. Or all over – whatever you prefer. Decorating the cake is almost as fun as eating it. (Almost.)

Like banana bread and carrot cake, I find that peanut butter cake tastes best on day 2 after the flavors have settled and have gotten friendly with one another. It is also more moist on the 2nd day as well.

slice of peanut butter cake topped with marshmallow frosting and chopped peanut butter cups on a white plate with a fork

So there you have it… a twist on the classic Fluffernutter sandwich we remember as kids. It’s simply the best peanut butter cake I’ve ever eaten. I was blown away by its flavor and just how easy it was to make. There is no excuse not to try this if you’re a Fluffernutter Lover. 😉

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slice of peanut butter cake topped with marshmallow frosting and chopped peanut butter cups on a white plate with a fork

Fluffernutter Cake

  • Author: Sally
  • Prep Time: 20 minutes
  • Cook Time: 32 minutes
  • Total Time: 3 hours
  • Yield: serves 10 1x
  • Category: Cake
  • Method: Baking
  • Cuisine: American


Rich and moist peanut butter cake topped with marshmallow frosting and peanut butter cups. It’s like biting into a fluffernutter sandwich, but better!




  • 1/2 cup (1 stick or 115g) unsalted butter, softened to room temperature
  • 3/4 cup (150g) packed dark brown sugar
  • 2 large eggs
  • 2/3 cup (170g) creamy peanut butter
  • 1 teaspoon pure vanilla extract
  • 1 and 1/4 cups (156g) all-purpose flour (spoon & leveled)
  • 1 teaspoon baking powder
  • 1/4 teaspoon salt
  • 1/4 cup whole milk or buttermilk*

Marshmallow Frosting

  • 7.5 oz (1 cup; 213g) container marshmallow creme (Fluff)
  • 8 oz (225g) cream cheese, softened to room temperature*
  • 1/2 cup (60g) confectioners’ sugar
  • 2 teaspoons pure vanilla extract
  • 1/2 teaspoon salt
  • optional: 8 Reese’s Peanut Butter Cups, chopped


  1. Preheat oven to 350°F (177°C). Spray a 9×2 inch cake pan (or 9-inch springform pan) with nonstick spray. Set aside.
  2. Make the cake: Using a handheld or stand mixer, beat the butter and brown sugar together on medium speed in a large bowl until creamed. About 2-3 minutes. Add eggs, one at a time, and beat until combined. Scrape down the sides of the bowl as needed. Add the peanut butter and vanilla extract, beating for about 2 full minutes. Set aside.
  3. In a medium sized bowl, toss together the flour, baking powder, and salt. Slowly add the dry ingredients to the wet ingredients in 3 additions, stirring by hand after each addition. Batter will be thick. Add the buttermilk and mix until just combined, do not overmix.
  4. Spoon the batter into the prepared cake pan. Bake for 20 minutes. Remove from the oven and loosely cover with aluminum foil. Bake for an additional 12-13 minutes or until a toothpick inserted in the center comes out clean. Allow cake to cool completely in the pan on a wire rack.
  5. Make the frosting:* In a medium sized bowl, beat the cream cheese on medium-high speed until smooth and creamy. Turn off the mixer, add the marshmallow creme and beat on low speed for 1 minute. Slowly add the powdered sugar and vanilla extract and beat for 1 minute. Add the salt and continue to beat. Add more powdered sugar if you’d like the frosting to be thicker. Add more salt to cut that extra sweetness.
  6. Remove the cake from the pan by inverting it onto a large plate or cake stand. Frost the cake as desired. There will be leftover frosting depending how much frosting you use. Decorate with chopped Reese’s Cups. Cake stays fresh (covered) at room temperature or in the refrigerator for 4 days. Frost immediately before serving.


  1. Milk: I like to use buttermilk in this recipe because it adds wonderful moisture and flavor. Whole milk is excellent too. You can use any milk, dairy or nondairy, but the lower fat milk you use, the less flavorful and moist your cake will taste.
  2. Frosting Alternative: If you are not a fan of cream cheese, I suggest making this marshmallow frosting instead (it is what I use to fill my marshmallow s’more cupcakes).
  3. Layer Cake: If you’d like to make this a double layer cake, simply double all of the ingredients and bake in two 9-inch round pans.

Keywords: fluffernutter cake

Reader Questions and Reviews

  1. Hi Sally, this cake looks AMAZING! (fellow peanut butter lover) just wondering, would it be possible to leave out the marshmallow topping if you’re not a fan? or would it be a bit bland iwthout it? 🙂

    1. Yes, you could leave the frosting off of the cake if you’d like. Maybe add 1/2 cup chocolate chips to the cake to add a little “something” to the peanut butter cake? Enjoy!

  2. Hi, i made this fluffernuttercake for my friend who is a big america-fan and it was such a success! thank u so much for the recipe and already converting the measurments! That was really helpfull. I was afraid that the frosting would be too sweet but it was just right!

    Thank u!

    Elodie from Belgium.

  3. Hi don’t know if you have been asked this already, would it change the taste to use light brown sugar instead of the dark brown sugar?

  4. I made this cake yesterday, and it was beautiful. The frosting was wonderful. The only downside was that the cake was very dry. I think that the baking time may have been a bit long for down south (used 9″ springform). I split the cake horizontally and essentially made two layers and put frosting in the middle – then covered and refridgerated overnight, which helped. I would definitely make this again, and cut the baking time.
    FYI – I thought the icing seemed familiar, and it is the same recipe that a friend uses for the best fruit dip ever. Amazing with strawberries!

  5. Hello, does anyone know the baking time for a 9*13 pan? I would like to make this for the holiday but I will need to double the recipe and would like to use a 9*13 pan instead of two rounds?

  6. Could you sub the Peanut Butter with Almond Butter. I would like to make one cake using Peanut Butter and the other with Almond, my father prefers Almond Butter to Peanut. I was also thinking of adding a Caramel drizzle to the Almond Cake as well.

  7. I made this for a 4th of July cookout. My husband wasn’t feeling good, so we stayed home and sent the cake with my nephew. The report I got was that the cake had rave reviews from everyone. Not a slice left! Just a note about the frosting–at the last minute, I found that the cream cheese I planned to use had gone moldy. With no time left to make a store run, I just substituted butter and put a bit of buttermilk powder in for some tang. It didn’t have the cream cheese taste I love, but it was still good. My nephew described it as a nice marshmallowy vanilla taste. Thanks, Sally! Another winner!

  8. Just made this yesterday for my husband’s birthday and he and the family loved it! I have never heard of a fluffernutter before but my Father-in-law grew up with eating them so this recipe took him back in time! Thanks so much for the recipe!
    I highly recommend this to all the peanut butter and chocolate lovers!!

  9. Hi Sally!
    Another HIT! Made this cake for my son for his birthday & he picked it up & RAN to his room! He said….THIS IS MINE! I am NOT sharing!

  10. Made this cake for my husband’s birthday as he loves fluffernutters. I was hoping for a rich moist peanut butter cake. Sad to report it ended up very dry. Not sure what I did wrong, every time I tried to do the toothpick test it was still gooey in the middle. Still tasty, just wish it was not so dry.

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