I Tried Making the 100-Hour Brownies – Here’s What Actually Happened
Yes, it really takes four days. And yes, I actually did it.
If you’ve been floating about online for more than five minutes, you’ve probably come across the 100-hour brownies. They’re one of those recipes that shows up in beautifully shot videos with soft piano music and someone whispering about “flavour depth” while slow-mo chocolate drips in slow motion.
So naturally, I had to try it. And as someone who’s always up for a bit of kitchen faff with the potential for greatness (or disaster), I committed to the full four-day journey. Here’s how it went — method included.
The Method (AKA: How to Test Your Patience in Multiple Stages)
Step 1: Brown the Butter
I kicked things off by browning the butter in a pan over medium-high heat. The smell was glorious — rich, nutty, and already a good sign of things to come. Once it hit that golden stage, I added a teaspoon of espresso powder and an espresso ice cube. That helped cool it down quickly, and I set it aside.
Step 2: Make the Batter Base
In a bowl, I cracked in four eggs, added a teaspoon of vanilla paste and about 200g of sugar. The original recipe calls for over double that, but honestly, I found this plenty. If you’ve got a bigger sweet tooth, go ahead and bump it up.
I whipped it all together with a hand mixer until the mixture turned pale and fluffy — almost mousse-like. Very satisfying that bit, I won’t lie.
Step 3: Add the Dry Ingredients
Next, I sifted in some cocoa powder, another spoonful of espresso powder, and salt. I gave it a gentle fold in with a spatula, keeping everything smooth and airy.
Step 4: Melt the Chocolate
I melted down a mix of dark and milk chocolate over a very low heat. You don’t want to rush this — it’ll burn and ruin your day. Once it was smooth, I popped it outside to cool (thank you British winter). Then, I folded in the browned butter, followed by the cooled chocolate. It looked outrageously glossy at this point. Dangerously eat-it-with-a-spoon levels of good.
Step 5: Add Flour and Chopped Chocolate
I sifted in plain flour and folded that through. Then I added chopped milk and dark chocolate. By now the batter was thick, rich, and absolutely banging. The espresso, chocolate and vanilla together just filled the room with this amazing smell.
Step 6: Into the Tin
I lined a ceramic baking dish with parchment, poured the batter in, smoothed it out, and topped it with even more chopped chocolate. Then I covered it with cling film and popped it in the fridge for its three-day nap.
The Long Chill (And Longer Restraint)
I left the batter in the fridge for 72 hours. Yes — three whole days. You open the fridge, you see it sitting there like a finished masterpiece, and you just have to shut the door and walk away. Over and over again. Utter torture.
Eventually, the big day arrived. I baked the tray at 180°C for 30 minutes. It was still a bit wobbly in the centre, so I gave it another 5–10 minutes. Once baked, I wrapped it in foil and carefully put it in the freezer for 30 minutes. Honestly, putting warm brownies into a freezer is a bit dicey. If you’ve not got a decent freezer, let them cool slightly first.
After that, they went into the fridge — or in my case, the back garden — for another 24 hours. Gotta love a cold British February.
Before serving, I cut a few slices and popped them into the oven for 10 minutes to reheat. That brought the gooey centres and crispy tops right back to life. Beautiful.
Final Verdict
So, were they worth it? Honestly… yeah. They were lush. Rich without being too sweet, full-on chocolate flavour with just a hint of espresso, and that classic brownie texture — crisp on top, fudgy in the middle, chewy on the edge. Exactly what you want.
Would I do it again every week? Not a chance. But as a one-off showstopper or a bit of a chocolatey experiment? Absolutely. Just plan your fridge space and prepare to be tempted every time you open the door.
Let me know if you give these a go — or if you cheat and only leave them in the fridge for a day. I won’t judge… much.
Watch the video above or here… the video that inspired it here… and for something similar check out these Oreo Cookie Dough Brownies.