Peanut Butter Mousse Brownies are fudgy brownies with creamy peanut butter mousse spread over the top, then garnished with chopped peanuts and chocolate syrup. It is the perfect dessert for those who love the combination of chocolate and peanut butter! If you are all about chocolate, I also have Chocolate Mousse Brownies you will love!

Stack of Peanut Butter Mousse Brownies on a wooden table surrounded by peanuts.
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Ingredients & Substitutions

Brownies: The brownie layer is the perfect fudgy brownie if you ask me! I have used this recipe for a few of my desserts like Snickers Brownies and French Silk Brownies, which you will also want to try! If you do not want to make homemade brownies, you could use a box mix, too. Simply follow the instructions on the box. Let the brownies cool before adding the mousse.

Cocoa Powder: Use Dutch-processed cocoa powder for the richest, darkest brownies. If using regular unsweetened cocoa powder, the brownies may have a different taste and texture. They will also be lighter in color.

Peanut Butter Mousse: This mousse is SO good, you will probably want to make it once the brownies have cooled. Otherwise, you may eat it all! (Okay, maybe that is just me…) Anyway, it is a smooth and creamy treat that you will want to have on hand to enjoy as a dessert on its own, too!

Peanuts: For a nutty crunch, I like to add chopped peanuts over the top of the mousse. You could leave those off if preferred; the brownies will still be delicious!

Chocolate Syrup: Drizzle a bit of chocolate syrup over the brownies as a finishing touch (and more chocolate)!

Pan of Peanut Butter Mousse Brownies with one missing from pan and on a plate.

Can I Make These Brownies Ahead Of Time?

Yes! You can get both the brownies and the peanut butter mousse made in advance. Once the brownies have cooled completely, store them in an airtight container at room temperature for a day or two. The peanut butter mousse can be made and stored in the refrigerator for up to a week.

Three Peanut Butter Mousse Brownies on a baking sheet with peanuts around.

How To Store Peanut Butter Mousse Brownies

Store peanut butter mousse brownies in the refrigerator, covered, for up to 3-4 days. For longer storage, freeze the brownies. If you are storing them in the container, I love this baking dish with a lid!

One Peanut Butter Mousse Brownie on a black plate with other brownies around.

Freezing Peanut Butter Mousse Brownies

To freeze the brownies, follow these steps:

  1. Once the brownies have cooled, spread the peanut butter mousse over the top.
  2. Chill the brownies in the refrigerator for about an hour to help the mousse firm up slightly.
  3. Consider cutting the brownies into individual servings or smaller portions if they are in a large baking dish.
  4. Wrap the entire baking dish or individual brownie portions (if cut) tightly with plastic wrap, ensuring it covers both the brownie base and the peanut butter mousse topping. Make sure the plastic wrap is sealed securely to prevent air from entering. You may also want to add a layer of aluminum foil.
  5. Label and date the packaging; they will last up to 2-3 months.
  6. When ready to enjoy, let the brownies thaw in the refrigerator overnight.
Peanut Butter Mousse Brownies in a pan on a wooden table from overhead.

Peanut Butter Mousse Brownies

Prep Time 15 minutes
Cook Time 35 minutes
Peanut Butter Mousse Brownies are fudgy brownies with creamy peanut butter mousse spread over the top, then garnished with chopped peanuts and chocolate syrup. It is the perfect dessert for those who love the combination of chocolate and peanut butter!


  • 1 ½ cups (187.5 g) all-purpose flour
  • 1 tablespoon cornstarch
  • cup (39 g) Dutch-processed cocoa powder
  • ½ teaspoon baking powder
  • ¼ teaspoon kosher salt
  • 4 large eggs, room temperature
  • 2 cups (400 g) granulated sugar
  • ¾ cup (1 ½ sticks / 170 g) unsalted butter
  • 2 teaspoons vanilla extract
  • 1 recipe peanut butter mousse, prepared
  • chopped peanuts, for garnish
  • chocolate syrup, for garnish


  • Preheat the oven to 350°F. Line a 9×13-inch baking dish with parchment paper up the sides.
  • In a large bowl whisk flour, cornstarch, cocoa, baking powder, and salt. Set aside.
  • To the bowl of a stand mixer fitted with the paddle attachment, add the eggs, sugar, butter, and vanilla. Beat on medium speed until light and fluffy.
  • With the mixer off, add the flour mixture. Turn the mixer on low and mix until the ingredients are well combined.
  • Pour brownie batter into the prepared baking dish and bake for 30-35 minutes, or until done. Fudgy brownies are done baking when the edges appear set, but the center is still shiny, or moist.
  • Let the brownies cool at room temperature.
  • Spoon the mousse over the cooled brownies and spread it into an even layer. Garnish with chocolate syrup and chopped peanuts.

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What the Test Kitchen had to say about this recipe:


Chocolate and Peanut Butter is a combination that most people crave, so it's no surprise how well it worked in this recipe. Creamy and light peanut butter mousse, on top of a dense and chocolatey brownie, and then finished with all of the toppings…this is a winner in my book!


I love chocolate and peanut butter desserts, and these brownies did not disappoint. But, call me crazy, I would add even more peanut butter! With the mousse brownies, it's like getting two desserts in one treat!


I love peanut butter with chocolate so these are right up my alley. I thought these were absolutely perfect!


Peanut butter and chocolate are such a classic pairing. The mousse on top is so creamy, it reminds me of ice cream! I loved this so much!

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Meet Amanda Rettke

Amanda Rettke is the creator of I Am Baker, and the bestselling author of Surprise Inside Cakes: Amazing Cakes for Every Occasion – With a Little Something Extra Inside.Over the course of her 15+ year blogging adventure, she has been featured in and collaborated with the Food Network, New York Times, LA Times, Country Living Magazine, People Magazine, Epicurious, Brides, Romantic Homes, life:beautiful, Publishers Weekly, The Daily Mail, Star Tribune, The Globe and Mail, DailyCandy, YumSugar, The Knot, The Kitchn, and Parade, to name a few.

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