Fudge Brownie Cupcakes with Peanut Butter Frosting

Fudgy brownie cupcakes covered in creamy peanut butter frosting.

Fudgy brownie cupcakes with creamy peanut butter frosting - these are unbelievable!

What is happening?? Has it really been over a MONTH since my last peanut butter recipe?!?? So shameful.

Let’s just make up for that disgrace with an over-the-top, yet completely simple cupcake. Or a brownie.  Or a brownie cupcake. I love these cupcakes so much! They’re easy, took me less than 45 minutes start to finish, and combine my favorite flavor combo on earth.

Fudgy brownie cupcakes with creamy peanut butter frosting - these are unbelievable!

The cupcake itself is so fudgy and rich, that I could almost just eat it plain.  But, I knew these fudgy brownie cupcakes were the perfect canvas for peanut butter. A ton of peanut butter frosting. And sprinkles.

So this frosting. OMG this frosting. Be still my little heart. I originally planned to top these fudgy brownie cupcakes with cream cheese frosting, but let’s be serious.  I immediately reached for the peanut butter jar after the cupcakes cooled. It’s a simple frosting recipe, really. And my secret ingredient is the heavy cream.

Trust me on this. Heavy cream, while bad for the thighs, is a frosting’s dream come true. It creates the smoothest, fluffiest frosting on earth. Plus, it makes the frosting sooooo easy to pipe or slather on the cupcake. And yes. It is impossible not to take a taste and lick the frosting bowl…

sidenote: I used a Wilton 1M piping tip to frost these. Feel free to just swirl the frosting on with a knife or use another piping tip.  I love the 1M though… it creates pretty swirls like a soft serve ice cream cone!

Fudge Brownie Cupcakes with Peanut Butter Frosting



  • 1/2 cup (1 stick) unsalted butter
  • 3/4 cup packed light brown sugar
  • 1/2 cup unsweetened cocoa powder
  • 1 Tablespoon vanilla extract
  • 2 large eggs, at room temperature
  • 1/4 teaspoon salt
  • 1/2 teaspoon baking powder
  • 2/3 cup all-purpose flour (measured correctly)

Peanut Butter Frosting

  • 5 Tablespoons unsalted butter, softened to room temperature
  • 1 cup creamy peanut butter
  • 1 cup confectioners' sugar
  • 1/3 cup heavy cream
  • 1 teaspoon vanilla extract
  • 1/4 teaspoon salt
  • chocolate sprinkles


  1. Preheat oven to 375°F (191°C). Line a muffin pan with cupcake liners.
  2. Make the cupcakes: Melt butter in the microwave in a large microwave safe bowl. Mix in the sugar until smooth and microwave for about 1 minute. Stir the mixture until smooth again. Whisk in the vanilla and eggs. In a separate bowl, mix together the salt, baking powder, cocoa powder, and flour. Slowly add to the wet ingredients and stir until completely combined.
  3. Fill the muffin tins about 2/3 full. Bake in the prepared muffin tin for about 8-10 minutes (mine took a little under 9 minutes). Allow to cool completely.
  4. Make the frosting: Beat softened butter on medium speed for 1 minute until completely smooth and creamy. Add the peanut butter and beat on medium-high speed until the two are combined. Add the confectioners' sugar, cream, vanilla extract, and salt. Beat on low speed for about 20 seconds, then gradually increase to high speed. Beat on high for 1 minute. Frost cooled cupcakes. Top with chocolate sprinkles, if desired.
  5. Make ahead tip: Cupcakes can be made ahead 1 day in advance, covered, and stored at room temperature. Frosting can also be made 1 day in advance, covered, and stored in the refrigerator until ready to use. Decorate/assemble cupcakes immediately before serving. Leftover cupcakes keep well covered tightly at room temperature or in the refrigerator for 3 days. Frosted or unfrosted cupcakes can be frozen up to 2-3 months. Thaw overnight in the refrigerator.


Recipe Notes:

You could easily use boxed brownie mix as a shortcut, but you would need to adjust the frosting accordingly since the peanut butter frosting recipe below only makes enough for 10-12 cupcakes.

Depending on how full you fill the muffin tins, you could get anywhere from 8-12 cupcakes. I fill mine about 2/3 full.

Did you make a recipe?

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© Sally’s Baking Addiction. All images & content are copyright protected. Please do not use my images without prior permission. If you want to republish this recipe, please re-write the recipe in your own words, or link back to this post for the recipe.

Peanut butter freak? Yeah, me too…

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  1. I have been drooling over these cupcakes for about a month now anf i am about to make them. I was just wondering if it would be ok if i used salted butter and omited the afditional salt….. Looking forward to hearing back from you!!!

  2. I’m thinking of using this frosting recipe for a 9-inch double layer cake..do you think there is enough it?

    Seems like a great recipe based on the reviews!!

  3. Hi! Can this recipe be made into a cake? Thanks! 🙂

  4. I would love to try this peanut butter frosting with your chewy fudge brownies with crushed peanut butter cups on top!…. Yummy!

  5. I CANNOT stop eating the frosting! A-okay!!!! I am also a peanut butter freak!

  6. hi!! I love your website and alllll of your recipes! So hard to choose so just have to make them all 🙂 
    I just made these and I had to cook them for 8 min longer than you said … And only got 8 out of the recipe and that was really scraping the edges of my bowl … I hope they aren’t over baked (I don’t eat chocolate lol) – but could I have done something wrong? I checked them at 9’minutes and they were raw in the center … 

  7. Hi Sally, Made a vegan version of these for friends and now they want more. Just a quick question as so many people want to try them if I was to make mini cupcakes how long would you need to bake them for?

  8. Hi Sally, Could you please tell me the flour quantity in grams ? Thank you 🙂

  9. I’m in love!!! So simple to make and so yummy; I did post a picture on IG.

    Has anybody tried the Marshallow Frosting with these?

  10. Hi! Can u use while milk instead of heavy cream?

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