brownie experiment

How to Make Brownies With a Crispy Top – Experiment-Along

Want a smooth, slightly crackly, top on your brownie, but no clue how to get there?

I started testing different hypotheses a little while ago, but quickly realized there were a few too many tins of brownies I had to bake! Join us in this experiment-along to find out how to achieve the perfect crispy top. We’ll bundle all of our “scientific” baking skills together to come to some proper conclusions on what it takes to make the ultimate crackly brownie tops.

What is a crackly top?

When we’re trying to explain what a smooth, crackly top is, images work best. What we’re looking for is a top that looks like brownie C in the photo below.

brownie experiment
Four different brownies, each made in a slightly different way.

Notice how the top of C is slightly glossy and has a few cracks and wrinkles in the top? Brownie C also had a little bit of crunch in the top too.

When I make a brownie, that’s how I always hope it will turn out looking. But, more often than not, it doesn’t. Sometimes, that’s probably due to me not following instructions properly (which I’m pretty good at, if I may say so πŸ˜‰). Other times, maybe the recipe just doesn’t work for making a top like this.

I’ve done a few experiments to try and figure out what influences the presence (or absence) of this crackly smooth top. But, power is in the numbers here. A few tests from one person can’t tell the full story. So, I’d like to invite you to experiment-along!

What’s a brownie?

A brownie is not a chocolate cake. Generally speaking, brownies are more fudgy and creamy, not light and airy like a cake would be. They’re a little denser. For the purpose of this experiment-along brownies need to contain milk and/or dark chocolate or cocoa powder. How much you’ll use differs a lot between different recipes.

For this experiment-along, use a recipe that you think represents a brownie. I’m just going to hope that our definitions of brownie don’t differ too much around the world!

How does an experiment-along work?

To join in the fun of the experiment-along, here’s what you need to do:

Option 1

  1. Read this whole article.
  2. Choose one of the hypotheses that I’ve stated below.
  3. Do at least one experiment to test the hypothesis, you can use your own (favorite) brownie recipe.

Option 2

Do any brownie-top related experiment you like, in any way or form that meets your liking! The only real criteria we have to participate is that you should be investigating the crackly tops of brownies, but how you do that is completely up to you. If you have another hypothesis that you want to test, go ahead!

Don’t forget to share your results!

  1. When experimenting, gather at least the following information:
    • The recipe you’ve used: ingredients + instructions (if you’ve used someone’s recipe, share the source)
    • A photo of the result
    • Your interpretation and thoughts.
  2. Report the results by:
    • Sending an e-mail to experiment-along OR
    • Sharing your results on Instagram and tagging us @foodcrumbles OR
    • Sharing your results on Twitter and tagging us @FoodCrumblesSci OR
    • Join the fun and join our experiment-along community! (need to create a free account to access, to prevent spam)
  3. Do so before September-30th
  4. Keep an eye out for a recap of all results in October-2022

The hypotheses

I’ve browsed the internet to gather hypotheses on what makes a brownie’s crackly top. Here are some of the most promising hypotheses I’ve come across. Some hypotheses may seem to contradict one another. Does that mean that one is wrong, if the other is right? Or are there a lot of different ways to get this crackly top?

I don’t know and need your help in finding it out. Keep in mind that these are hypotheses. That means that we think they might be true, but we’ll only know for sure once we’ve done tests and proven whether they’re correct or incorrect.

1. Whipped eggs are key

You can only get a crackly top by whisking the eggs into a light and fluffy foam. Gently fold these into the brownie batter and bake immediately.

Note, this hypothesis would mean that it’s not possible to get a crackly top without eggs (or proper egg replacers). Is that true?

Sign up to our weekly newsletter to be updated on new food science articles.

2. Creaming sugar & butter is key

You have to cream the butter and sugar before adding in any dry ingredients.

Note, this hypothesis would mean that recipes that use molten butter or oil won’t work?

3. Mixing sugar into molten butter & chocolate is key

You have to melt the butter and chocolate first and add the sugar while the butter and chocolate are still hot.

4a. More chocolate = less crust

You do not need molten chocolate to make a crackly, crinkly top. On the contrary, the less chocolate (and more cocoa) the higher your chances of a crackly top.

4b. More chocolate = more crust

More molten chocolate gives a higher chance of a crackly crust.

Yes, this hypothesis directly contradicts 4a, but I found both statements online.

5. Refrigerate the batter

Refrigerate the brownie batter overnight and your crackly top will improve.

6. Use icing sugar

Using icing sugar instead of granulated sugar helps to create a crackly crust.

Note that icing sugar and powdered sugar are the same thing. What’s important here is the particle size and fineness of the sugar you’re using. A fine icing sugar will behave differently than sugar consisting of larger sugar crystals.

This hypothesis does make me wonder, does the type of sugar (e.g. brown vs. white) make a difference as well?

icing, brown and granulated sugar
From left to right: icing sugar, brown sugar, granulated sugar.

FAQ & tips on experimenting

Which brownie recipe should I use?

That’s part of the experiment! Choose whichever recipe you want. Either use one you’ve made before and like, or find one that you think might be able to create such a crackly top.
I’m pretty sure not every brownie recipe can result in a crackly top. But knowing which ones don’t work is helpful as well!

How do I do an experiment?

Whenever experimenting like this it is important to test only one variable. That means that when you’re making two batches of brownies, you keep everything the same, except for one thing. For instance, you can make two identical brownies, except for the type of sugar you’re using.
Experiments are quite simple if you’re just comparing one to one. However, you can make experiments more complex and change several things in a controlled manner. Make things as easy or as complicated as you’d like!

Can I win something?

Honor and a fun contribution to brownie science! This is the first experiment-along. If it’s a success, maybe I’ll add in some fun prizes in the future.


Tessa Arias, How to Make Brownies with Shiny Thin Crust, Handle The Heat, May-3rd, 2021, link

Emma Christensen, Perfectly Sweet: How to Get a Crunchy Top on Brownies, Kitchn, Oct-26, 2009, link

Cakewhiz, How to Make Fudgy Brownies With Crackly tops, Nov-5, 2015, link

Newsletter Updates

Enter your email address below to subscribe to our weekly newsletter

One comment

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.