We Made 100-Hour Brownies to See If This Recipe Is Worth the Wait

Updated: Oct. 11, 2021

To test this recipe, we made one batch of 100-hour brownies and one batch baked right after mixing. Here's what we discovered.

When you crave something chocolaty and comforting, it’s hard to think of anything better than a quick batch of brownies. Well, what if the recipe took days to make? Could 100-hour brownies be worth the wait?

This question was on everyone’s mind after Alvin Zhou, a producer for BuzzFeed’s Tasty videos, shared “100-Hour Fudgy Brownies” on his YouTube channel. The video shows Alvin steadily moving through the steps to make his brownies, like browning butter, whipping eggs and chopping chocolate, before stashing his brownies away for an excruciatingly long wait.

Fans of this 100-hour brownie recipe have spoken, saying that they’re the best brownies ever. Well, we had to find out for ourselves.

How to Make 100-Hour Brownies

flat lay of ingredients for 100 hour browniesNancy Mock for Taste of Home


Butter mixture:

  • 1 cup (2 sticks) unsalted butter
  • 1 tablespoon espresso powder
  • 1 coffee ice cube

Batter mixture:

  • 4 large eggs
  • 1 tablespoon vanilla paste or extract
  • 2-1/4 cups granulated sugar
  • 1/2 cup Dutch-processed cocoa powder
  • 1 tablespoon espresso powder
  • 1 tablespoon kosher salt
  • 8 ounces 75% cacao chocolate, melted
  • 1-1/2 cups all-purpose flour

Chopped chocolate:

  • 3-1/2 ounces chopped milk chocolate
  • 3-1/2 ounces chopped 75% cacao chocolate
  • 6 ounces chopped 75% cacao chocolate, for the topping

Editor’s Tip: This is the difference between natural and Dutch-processed cocoa powders.

Making the Brownie Batter

brownie batter in bowl for 100 hour browniesNancy Mock for Taste of Home

Alvin Zhou’s recipe begins by browning the butter to give it a deeper color and flavor. Don’t skip this step because it adds so much to the brownie experience. (Follow this guide to learn how to brown butter if it’s your first time.) Espresso powder is then stirred into the browned butter, which blooms the flavor, along with a coffee ice cube to cool the mixture.

While the butter cools, eggs and sugar are whipped until light before adding the cocoa powder, more espresso powder, salt, flour and melted chocolate. The espresso-butter mixture is then stirred in to create a ridiculously rich batter.

Stir in the chopped dark and milk chocolate pieces, then spoon the batter into a pan—13×9-in. for thin brownies, or an 8-in. square pan for thicker slabs. The final step is to sprinkle more chopped, dark chocolate over the top.

The First Wait

100 hour brownies batter in tinNancy Mock for Taste of Home

Here’s the hard part: You have to wrap that pan and put it in the fridge for three days.

You read that right. These brownies get chilled for 72 hours. If you’re like me your first question is why—why do we have to wait so long?! I asked Taste Of Home Test Kitchen experts to weigh in.

The long chill will allow the flavors more time to “marinate together,” says senior food stylist Shannon Norris. She adds that having cold batter will also keep it from over-baking.

Deputy culinary editor James Schend told me that the long rest will also let flour fully hydrate, giving the batter a deeper color and creating brownies that are dense and moist.

Bake, Then Wait Again

After three days in the refrigerator, it’s time to bake. They go straight into a 350°F oven to bake for 30 minutes (or 45 minutes if you’re making thicker brownies in a square pan.) When you pull the pan from the oven, the brownies will be wobbly in the center, so you know they’re going to be fudgy.

And then comes another long wait. Cover the top of the pan in foil and pop the hot pan into the freezer for 30 minutes. Alvin Zhou says he learned this trick from a pastry chef to help keep moisture in the brownies. After 30 minutes, the brownies go back into the fridge for 24 hours, to cool all the way through and set the texture.

The Final Result

Normal Vs 100 Hour Brownies Side By SideNancy Mock for Taste of Home

All that waiting was really hard, but you know what? The brownies were absolutely incredible.

To really understand the difference, we made two batches of this recipe: the 100-hour version and one baked right after mixing. When you put the sliced brownies from each batch side by side, you can see the difference. The normal brownies have the cakier crumb texture you expect, and because the top sank as the brownies cooled they were chewy, too.

But the 100-hour brownies? As our Test Kitchen experts predicted, these brownies were fudgy with a texture so soft and smooth it was almost mousse-like.

The flavor was so deep, buttery and chocolaty, it really was exquisite. The chunks of milk and dark chocolate inside were lovely to sink our teeth into. We also noticed that the dark chocolate in the normal batch retained its bitterness, but in the 100-hour brownies, the bitterness was gone.

finished 100 hour brownies cut into squaresNancy Mock for Taste of Home

Would We Make 100-Hour Brownies Again?

Even for such ridiculously delicious brownies, four days of prep isn’t always an option. But for special occasions? Yes, we would absolutely make 100-hour brownies again! They’re one of those dessert experiences that people will love to say they’ve been a part of.

Even for our normal brownie cravings, this recipe teaches us some techniques worth remembering for a flavor that that excels. Using nutty and fragrant browned butter, adding coffee or espresso powder and adding a blend of milk and dark chocolates make a more flavorful creation. Resting the batter before baking will let flavors meld and deepen, even if it can’t be a full 72 hours. And chilling the brownies after baking will help with that fudginess.

Then we can finally take a bite and sink into a delightful, dreamy brownie haze!

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