Today we will talk about one of the most buzz topics in the macaron baking world: hollow macarons. Why are my macarons hollow? How to fix hollow macarons? We will cover it all!
Recently I wrote a full Macaron Troubleshooting post. And when I went to write about hollow macarons, it got way too long, so I felt like this topic deserved its own post. So here we go! Let’s dive right in and find out why your shells are hollow!
Why are my macarons hollow?
This is probably the question I get the most!
And that’s probably because this is the most mysterious issue to troubleshoot. There’s just such a huge range of factors that can impact the fullness of your macarons.
The list you will see below may seem contradictory, such as: under baking, or over baking will cause hollow shells. However, that’s because it could be one or the other, and when it comes to macarons, you want precision. You want to find the sweet spot between over baking and under baking, which could be a difference of 2 minutes, or 5 degrees.
My biggest recommendation for troubleshooting hollow macarons is: once your macarons look perfect on the outside, the feet are awesome, the shells aren’t soft or crispy, the bottom looks nice and smooth, that’s when you should worry about troubleshooting hollows.
If your macarons are hollow with spread out feet, then figure out the feet first. If your macarons are hollow and with a soft shell, figure out the soft shell first.
Many times, the hollowness is a product of those other issues. So figure out how to perfect your technique so that the structure of the macaron is perfect, and then you can worry about hollow macarons.
Pockets of air or gaps in the shells
Sometimes your macarons have pockets of air in them, so they aren’t completely hollow, but they still have these gaps like in the examples below.
Sometimes the air pockets are like this, just random holes in between full shells.
Or sometimes they might be gaps between the top and the middle of a somewhat full shell like such.
Sometimes, those hollow pockets or gaps will fill up as the macaron sandwiches mature for 24 or 48 hours. However, sometimes they won’t. Use the same troubleshooting below for pockets of air and gaps as you would for a completely hollow shell.
The pockets and gaps are way more likely to fill up, and indicate you are much closer to a full shell, and all you have to do is tweak a bit here and there, and you will get there!
What causes hollow macarons
Over mixed batter
Over mixed batter may cause hollow macarons. Sometimes your macarons may be looking like they have a nice shape, and the feet look nice, but folding a bit less will help solving hollows.
Experiment going easier on the folding and see how that goes. Even if your batter seems fine and flowing slowly but effortlessly at the figure 8 stage, just try folding a bit less next time.
This solved my vegan macaron hollow issues! And it will also work for egg white macarons.
Under mixed batter
Under mixed batter may cause hollow shells. However, you will definitely be able to tell, because the macarons will have a pointy top.
If your macarons have points on the shells, and they are hollow, then do the macaronage a bit longer next time.
Check out my videos on YouTube where I show the perfect macaronage stage in each video.
High oven temperature
High oven temperature could be the culprit for hollows. Sometimes only 5 degrees can make a big difference.
If your shells look perfect on the outside and you have hollow macarons, experiment with lowering the temperature by 5 or 10 degrees, pipe the batter between different trays, and experiment with different baking times/temperature within that range. Write down your results and see what you come up with.
Always have an oven thermometer to be able to tell the temperature inside the oven.
This is the thermometer I use:
Please read more about the oven here and how important it is to figure out your oven to make perfect macarons.
Low oven temperature
Low oven temperature can cause hollow macarons, because the inside of the shells isn’t having a chance to bake enough, so it’s not drying, which will cause the shells to be hollow.
Experiment with higher temperatures if you are staying on the low side, specially if your temperatures are below 300 Fahrenheit.
And like I’ve said above with the high oven temperature issue, just pipe the batter between different trays, and experiment with different baking temperatures and times within a 5 to 10 degree range. Write down the results always.
And also try to do this experiment with the same batch, to make sure that there aren’t other aspects affecting the results such as the meringue, macaronage, weather. But also continue to experiment with different batches if you don’t come to a conclusion.
Under baked shells
This is a big one right here. Under baking is known to cause macarons to become hollow.
That’s because if you under bake the shells, you won’t give the inside of the macarons a chance to dry and cook. So basically the inside of the shells simply won’t form, won’t have a nice structure.
To make sure your macarons are fully baked, try to wiggle a shell while still in the oven, if it jiggles, it needs more baking time.
If you are still uncertain, or having issues with telling if the macarons are done baking, remove one of the shells and cut it in half. If the middle of the shell is gooey, then the shells need a bit more time baking.
And if you are worried your macarons are getting too brown on the outside and not baking on the inside, consider covering the macarons with foil halfway through baking, or experiment with lower oven temperatures.
Resting too long
Resting the shells for too long will cause the macarons to be hollow, because the if the macarons sit for too long the meringue will loose stability. And the meringue’s stability is very important for the structure of the macarons.
Another aspect I noticed with over resting is that the top of the macarons will basically detach from the bottom, leaving a gap between the feet and the top of the shells.
And specially if you are in a humid climate, it’s important to find recipes that will call for no rest methods, as leaving your macarons resting on a humid climate is going to make them absorb the humidity, breaking down the meringue even faster.
Recipes that don’t call for resting usually have a higher ratio of powdered sugar/ almond flour to egg whites/ granulated sugar.
You can also experiment with adding egg white powder (not meringue powder) to the shells, as the egg white powder will add more protein to your meringue without any of the added moisture that the egg white usually has.
This is the egg white protein I use:
I add 4 grams of egg white protein for each 100 grams of egg whites, like I do on this recipe: Fig Macarons.
And some bakers also add cornstarch to their recipes to help this issue! On my French method recipe, I use a high ratio of almond flour and powdered sugar to egg whites and granulated sugar, and I also use cornstarch on the recipe, check out this Coconut Macarons recipe.
Checking your meringue will be very important in trying to combat hollows.
Under whipped or over whipped meringue may cause hollows, because in both cases the structure of the meringue isn’t properly developed, which will affect each aspect of the macaron.
Under whipped meringue won’t have a stable enough structure to keep the air and water particles in place, and it won’t have enough air particles in it for that matter.
And over whipped meringue will have a broken and collapse structure which will also not be able to keep the air and water particles in place.
Please read this post, in which I explain the science behind the meringue and why it’s so important for it to be properly whipped.
Make sure the meringue is stiff, with peaks that shoot straight up. If the meringue has long peaks that are bending to the side, it’s too soft. And if the meringue is separating into chunks, it’s over beaten and therefore broken.
I hope today’s post was very informative, and that you were able to understand a little better what causes hollows, and how to fix hollow macarons.
For more information please visit the Macaron School page containing all the important articles that can help you learn macarons.
Here are some of them:
- The most important stages of making macarons
- How to make perfect macarons
- Frequently asked questions (coming soon)
- Understanding your oven
- Macarons for beginners
- Tools I use to make macarons (coming soon)
- Meringue lesson
- Troubleshooting Macarons
And for my complete list of macaron flavors visit this page.