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

Ingredients:

Cupcakes

  • 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

Directions:

  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.

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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.

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84 comments

  1. Can this recipe be turned into a cake recipe at all? I think I need a little more than a cupcakes worth of this!!

  2. So… I officially have my new favorite cupcake! My sister baked them for a party a few days ago, and they were the best cupcakes I’ve ever had!

  3. I borrowed your peanut butter frosting recipe to go with my own fudge brownies. I may or may not have eaten the last 1/2 cup straight from the bowl. I now intend to work my way through every peanut butter related recipe on this page. Thanks for giving me a goal to reach for!

  4. Hello Sally..the recipe looks delicious…can you tell me what is a ‘heavy cream’ that u use for the frosting?

  5. Hi sally,
    First i wanna say thank you for being generous. Its really amazing of you to share ypur tummy recipes. I followed your choco chip cookie cake and my boyfriend loved it! He couldnt get enough of it. 🙂 now i only look at your website for yummy recipes. I cant wait to try all your recipes. And this recipe is next in line. Im planning to make this for my moms birthday. But im planning to make 1 giant cupcake out of this recipe. Any suggestions? Should i double the recipe? I read somewhere a recipe that makes 24 cupcakes makes 1 giant cupcake. Is this true? Once again thank you for your timw. You are kind.

    • Hi Oj – thank you for your sweet comment. Unfortunately, I am unsure about the giant cupcake. I’ve never made one, to be honest.

  6. Can the brownie cupcakes be made in mini form, made ahead and frozen?

  7. Hi Sally! I tried your cupcakes they were amazing! I just wanted to know that if some day i am short of butter or its not available can i use oil and if yes that what about quantity?
    Thankyou

  8. Hi Sally!

    These look amazing. I was just wondering what type of coco powder you used? Sweetened or unsweetened?

    Thanks!

  9. OMG Sally, this peanut butter frosting is heaven!!! And it was so perfect with the brownie! My boyfriend said that it should be made into a cake 😉

  10. I made this frosting out of an intense craving for sweets two weeks ago. So incredibly good – I honestly think it may be your best one! So fluffy and not too sweet. Honestly, addicting.
    I was originally going to make some of those “No Pudge” Fudge brownies (it’s a low cal option to brownie box mix – all you add is greek yogurt!) but once I made them they were just begging for a frosting! lol I loved that it was a large portion of frosting. I let it set in the fridge overnight so that I could cut them into heaping squares to take to work the next day. Everyone at work was so enamored, I sent out the link to the recipe in several emails!

  11. 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!!!

  12. 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!!

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

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

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

  16. 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 … 

  17. 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?

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

  19. 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?

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

  21. Hey Sally,

    Can I sub coconut milk for the heavy cream? Would I stick with the same measurement as the cream or make adjustments?

    Thank you for all the great recipes!!

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