Love and Olive Oil

Chocolate Mousse Brownies

Chocolate Mousse Brownies from @loveandoliveoil

I can never settle for just a plain brownie. Instead, my mind is always thinking of what I can swirl, drizzle, frost, or fill them with next.

No matter how fancy I might get, however, the base is equally as important as any toppings or add-ins. You can’t mask a bad brownie with frosting. While I used to be a die-hard proponent of chocolate-based brownies, I’ve been experimenting more and more with cocoa brownies. Probably because they are way easier (no double boiler nonsense or chopping chocolate). I’ve had mediocre results before, but these hold their own against my previous favorite. The secret, I think, is lots of butter (just say no to vegetable oil) and way more cocoa powder than you think is reasonable. Seriously, don’t skimp. I buy big 2-pound bags of the stuff just so I’m never short.

Chocolate Mousse Brownies from @loveandoliveoil

The chocolate mousse topping is lighter and less sweet than a buttercream; the rich chocolate flavor further deepened by the espresso powder (yet the coffee flavor is not as apparent as you might think it would be. If it were, I’d have called these mocha mousse brownies). The gelatin in the mousse makes it firmer than a mousse you might serve in a cup – which is necessary if you have any hope of getting clean cuts when you slice your brownies.

Chocolate Mousse Brownies from @loveandoliveoil

Have I mentioned I hate cutting brownies? It is not easy to get clean cuts, especially with layered brownies. While I know that roughly cut brownies don’t taste any less delicious, I love seeing the layers in crisp perfection. Over the years, while I still struggle with getting photo-worthy slices, I have learned a few tricks for clean cuts:

  • Chill out. Don’t rush. I usually let my brownies chill overnight before I even attempt to cut them. I know, it’s hard to wait when faced with an aromatic pan of brownies just out of oven, but they’re really better the next day, I promise. The overnight chill makes them even fudgier. And easier to cut.
  • Stay sharp. Some people say plastic doesn’t stick, but I have a hard time using plastic knives. I pull out my biggest, sharpest knife, and try to get one smooth cut. Don’t saw. Cut down, and carefully slide it out. Then wipe off the knife before making another cut. Sometimes warming the knife slightly under hot water can help also.
  • Measure twice. Or at least, measure once. Yes, I totally get out the ruler when cutting brownies. My eye just isn’t that good. If I don’t measure first I end up with uneven sizes and non-square squares.
  • Be a square. If you can, invest in a nice 8×8 pan with square corners (I have this one). Then you won’t have any brownies with ugly rounded corners or waste any trimming off the edges (although, I admit, the trimmings make excellent snacks).

I could also see this becoming an elegant ‘black and white’ brownie – with white chocolate mousse on top and tuxedo-like drizzles of dark chocolate.

Chocolate Mousse Brownies

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For Brownies:

  • 1/2 cup (1 stick) unsalted butter
  • 3/4 cup dark or dutch process cocoa powder, sifted
  • 1/2 cup packed light brown sugar
  • 1/2 cup granulated sugar
  • 2 large eggs
  • 1 teaspoon vanilla extract
  • 1/2 teaspoon instant espresso powder
  • 1/2 teaspoon kosher or fine sea salt
  • 1/2 cup all-purpose flour

For Mousse:

  • 1/2 teaspoon unflavored gelatin
  • 4 ounces dark or bittersweet chocolate, shaved or very finely chopped
  • 1 cup heavy cream, divided
  • 1 teaspoon instant espresso powder
  • 1 tablespoon granulated sugar


  1. Preheat oven to 350 degrees F. Line an 8-by-8-inch square baking pan with parchment paper.
  2. Melt butter in a microwave safe bowl. Add cocoa powder, sugar, and brown sugar and stir until it forms a thick, grainy paste. Add eggs, vanilla, salt, and espresso powder and whisk until smooth. Fold in flour until just incorporated and no streaks of white remain. Spread into prepared pan and bake for about 25 minutes or until a toothpick inserted near the center comes out with a few moist crumbs attached. Remove from oven and let cool completely.
  3. To prepare mousse topping, in a small dish, sprinkle gelatin over 1 tablespoon of cold water and let sit for 5 minutes to soften. Place shaved chocolate in a heat-proof bowl.
  4. In a small saucepan, warm 1/3 cup of the heavy cream until steaming. Whisk in softened gelatin and espresso powder until dissolved. Pour warm cream over shaved chocolate. Let sit for 20 to 30 seconds, then gently whisk until smooth.
  5. Place remaining 2/3 cup heavy cream and granulated sugar in a large bowl or the bowl of a stand mixer fitted with the whisk attachment. Whip on medium-high speed until it forms soft peaks.
  6. With a large rubber spatula, fold in half of whipped cream to chocolate mixture to lighten. Add remaining cream and gently fold, scraping the sides and bottom of the bowl, until mousse is uniform in color.
  7. Spoon mousse on top of cooled brownies, and smooth into an even layer with an offset spatula. Do this fairly quickly, as the gelatin will begin to set up fairly quickly and the mousse will be much harder to spread smoothly.
  8. Lightly cover with plastic wrap and refrigerate until set, at least 2 hours or overnight (if possible).
  9. To cut, lift out entire block using the parchment paper as handles. Cut into a 4×4 grid of squares (or smaller if you prefer) using a sharp knife, wiping off knife between cuts. If desired, drizzle with melted chocolate for garnish before or after cutting into squares.
All images and text © / Love & Olive Oil

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  1. I made this for a charity baking group I belong to. Turned out great and much admired. We trimmed 1 cm off one end to taste before packing and sending off. Is delicious. You can see it here (staged the photo for Good Bitches Baking charity NZ)

  2. I made these brownies on the weekend for my son’s first birthday and they were amazing! The mousse was so much better than a buttercream and the flavour of these was great.

  3. I’m 15 and just made this for my mom for Mother’s Day and everyone loved it!! But the process in making it was rough, so one suggestion from me is make the mousse filling first so it has a lot of time to set/ not be liquid and even maybe make the day before you want the cake because the mousse was super runny since I didn’t let it harden enough and it made a mess. As o already said though the next day it turned out amazing and the icing is awesome!! 

  4. I made these last night and these are amazing! 

  5. These brownies look delicious! Can they be frozen?

  6. Can I use shortening besides butter allergic

  7. This looks almost too good to be true! yum! 

  8. I’m not usually one for frosted brownies (I think the brownies themselves are decadent enough) but something about the chocolate mousse sounds just right. I’ll have to keep these in mind next time I’m in a chocolate mood!

  9. How can I store these? I made them today (so delicious), but I am planning to bring the rest to an event on Thursday. Fridge, freezer, or what do you recommend? 

  10. As soon as I read your post and recipe I looked at the clock to see if I had enough time to prepare, bake, cool, refrigerate and frost. I was flyinggggg!  I’m sure I looked nuts! haha Fun night out with friends, they will love these! The mousse is ridiculous! Thank you.

  11. These look absolutely divine!

  12. Hi, can I substitute the dutch process cocoa with baking chocolate? I want to make them now, but dont have enough cocoa…thanks!

  13. Oh my, this looks SO delicious. 

  14. I’ve use a pizza cutter to cut brownies. Never had any problems. Works like a charm. You need a decent pizza cutter though. Cheapies probably won’t work. 

  15. Beautiful brownies! I agree; I’m not happy with plain brownies either. I love experimenting with my brownies to see what I can come up with. 

  16. Loving these brownies!! beautiful pics Lindsay! :)

  17. you legit took the words out of my mouth as I saw that first pic and thought DAMN, this girrrl cuts her brownies perfect!!! really appreciate the tips, and I especially agree about the cut down/slide move with an extra sharp knife – fighting it only makes things a mess!! looks faboosh Linds :)

  18. Oh this looks so stinkin good! I have not been thinking of anything but chocolate today… i have a good feeling this could satisfy my sweet tooth! Mmmm! Thank you for sharing – love your recipes! xo

  19. I love the mousse on top – so yummy! And great cutting suggestions – I have a special knife for cutting brownies, cakes, etc.  Perfectly sharp!  :)

  20. Yummy! I made peanut butter mousse topped brownies before which were also fantastic.

  21. Wow – these brownies look incredible! Such a decadent treat. I bet that mousse is divine :)

  22. I agree, plain brownies are boring! Brownies need a little something added to make them special. These look spectacular!

  23. I’m definitely a failure at cutting brownies properly, because I just want to eat them right away! love the chocolate-espresso action in these.

  24. my goodness. I am a chocolate mousse lover and this recipe looks amazing!

  25. These brownies look amazing. Thanks for the tips on cutting the perfect square. I can only wish to get that clean cut. My husband would never let a brownie sit for 24 hours; he can barely wait 10 minutes.

  26. Mmmmm, I could definitely go for one or two of these brownies right now. They look phenomenal!!

  27. this is amazing and such a good remedy to spicing up the regular brownie!! X

  28. Cutting layered brownies really is such a pain! Thanks for your tips!! And these brownies look so so delicious, love the layer of mousse. So good! Pinned :)

  29. Oh My! These look heavenly!

  30. What a perfect dessert, love the combination of chocolate and coffee:)

  31. Chocolate mousse… forgive me while I droooool!

  32. I am totally the same, plain brownies are just so so. I love the mousse topping, great idea.

  33. Unreasonable levels of cocoa and butter is where it’s at! Of course, no brownie in my life will be complete without chocolate mousse now…and I’m more than OK with that.

  34. I love the idea of mousse topping a brownie even better than frosting!! I hope you do make a tuxedo version…SOON!! :)

  35. These look great and great tips too! I just made Nanaimo Bars last night and I went to great lengths to get them cut nicely and not ruin the layers! This square baking pan is a must and it’s on my “to buy” list. Thanks, Lindsay!

  36. Wow, they look amazing! I will have to try them tonight I think… :)

    • So I tried them and they turned out great!! I prepared the cake again yesterday, double the recipe, as I’ll bring it to a birthday. Turns out I only used half the butter the first time for some reason. It was fine but this time I took the right amount and might use some fresh mango as well… I love the recipe!! Thank you for sharing.

  37. These look so perfect and delicious!  I am definitely following your advice on cutting brownies – it is so hard to avoid getting crumbs all over the place.  Next time, I am waiting overnight for them to cool!

  38. Yep, pretty sure this is what you get at the gates of Heaven.

  39. Yum and double yum! Can’t wait to try them!

  40. These look so fudgy. Love that light mousse topping!

  41. I too love how creative you are.  Seriously, chocolate mousse topped brownies!  Love it.

  42. These are beyond divine… I have always left my brownies just the way they are.. but I’d make the exception for that choco mousse topping!!

  43. I loooooove the mousse on these brownies! So yummy!

  44. I just wanted to thank you for those cutting tips! Obviously these look amazing,  but I was most struck by how beautifully square and perfect these are and was totally going to ask if you had any tips!  Yummy and pretty!

  45. These are so pretty! I love the mousse topping :-)

  46. Amazing! Now a regular brownie will seem extra boring after seeing these ;)

  47. I am more prone to chocolate brownies too…but these look so incredible that I just may need to switch! I’m always looking for ways to make over the top brownies too…and these are perfect for that! Love the espresso addition! Pinned

  48. These brownies are so gorgeous! I used to make plain brownies, but now I am just dying to try these!

  49. Yummmmy! ??

  50. I love how creative you are when it comes to brownies Lindsay! The idea of a squidy layer of brownie topped with a creamy chocolate mousse sounds totally out of this world. 

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