Home Made French Croissant – Science of steam & yeast

To be honest, I never thought I would ever try making croissants myself. Whenever reading about croissant dough (or puff pastry) I decided to stay away, it seemed far too much of a hassle. Folding in butter, cooling, folding, it just didn’t seem worth it. But then I got into a baking craze thanks to James Morton’s book Brilliant bread. While making various breads on the same day, I decided though, that it was time to try and make French croissants. And boy, it was worth it, they were delicious!

Before sharing the recipe though, we have to discuss “croissant science”.

Croissants are laminated = layered

One of the most important characteristics of croissants is their layered structure. Grab a croissant (or have a look at the photo below) and you will know what I mean. A croissant consists of a lot of very thin and crispy layers of dough with space in between.

If this reminds you of pie crusts, you’re very close. In both pie crusts and croissants it is butter that makes this flaky or layered structure. When baking the croissants in the oven the butter will melt. Since the butter prevented the two flour layers from coming together they will not merge, instead, where butter used to be will be a light air pocket. The fat will flow in with the dough.

layer structure of a croissant

Forming the layers in a French croissant

When making french croissants the hardest and most time consuming task is to create these layers in the dough.

In a pie dough the flaky crust is made by rubbing butter through flour, before mixing it with water or milk. This way, discrete pockets of butter remain in the crust. In a croissant the procedure is slightly more complex. Since we want these many thin layers, we have to make sure a lot of layers of butter are made. This cannot be done by simply rubbing in butter. Instead,we literally have to fold the butter into our french croissant dough.

French croissant dough

Even though croissants look similar to puff pastry, with all their layers, it isn’t. The main difference between the two is that croissants are made with a yeast dough that is risen as well, whereas puff pastry doesn’t use any yeast. We will come back to the effect of those differences later, but let’s first zoom in on the croissant dough.

The dough for a French croissant is very similar to that of a normal bread dough (see below for complete recipe). The main difference is that it uses less salt, more sugar and milk instead of water. Leaving the dough to rise and rest will develop a richer flavour than when using it immediately. Honesly, I haven’t tried without leaving it to rise, but I trust the science here.

Folding in the butter layers

Once the dough has been made and has risen (thus become more flexible, softer and easier to handle) the butter can be folded in. This is as simple (and at the same time as complex) as it sounds. The dough is rolled into a large rectangle onto which a layer of butter (half the size of the rectangle) is placed.

The dough is folded double and rolled out again. By folding the sides to the middle and then folding them to the middle again you create all the different layers. This process of rolling and folding it repeated several times.

When folding the butter in the dough it is very important the butter remains cold. If the butter warms up too much the fat will melt and merge with the dough. This won’t make a nice layered structure anymore. Putting the dough in the fridge between these rolling and folding sessions is therefore important.

The resting time in the fridge has another advantage. It relaxes the gluten which makes it easier to roll out again.

rolled out dough for french croissants
Croissant dough finished after all the folding and ready for rolling into little mini croissants.

What causes the puffiness

In a croissant there are two main factors which causes the croissants to puff and rise:

  1. Steam: both the dough and the butter contain moisture. When croissants are baked in the oven, the water will evaporate and form little steam bubbles. These bubbles expand because of the heat and actually help in creatig that layery structure by pushing apart the different dough layers.
  2. Yeast: yeast produces gas (carbon dioxide) when growing and fermenting in the dough. These gas bubbles expand in the oven due to the heat, pushing apart the different layers again.

Now that you know what french croissants are and how they become croissants, it’s time to share the recipe. Good luck with this little adventure, it will be well worth your time!

The recipe for French croissants

The recipe I used is described below. As mentioned at the top of this post, I found this recipe in the book Brilliant bread by James Morton, but I modified little bits.

Home Made French Croissant - Science of steam & yeast
Author:
Serves: 6 large or 12 mini croissants
Ingredients
  • 160g flour
  • 10g sugar
  • ½ tsp instant yeast
  • ¼ tsp salt
  • 100g milk
  • 40g poolish (see note below recipe, this can also be substituted by another 20g flour and 20g milk or water)
  • 100g unsalted butter
Instructions
  1. Mix the flour, sugar, yeast, salt and milk in a bowl.
  2. Leave to rest for 30 minutes (you can skip this if you're in a hurry, but it makes the bread easier to handle).
  3. Knead the dough until it has become considerably softer. You can do this in a stand mixer at speed 2 for approx. 10 minutes.
  4. Leave the dough to rise, either for at least 1 hour at room temperature or for >6 hours (or overnight) in the fridge.
  5. Knead the dough to push out the air bubbles and roll out in a flat sheat. The dough shouldn't stick to your surface, if it does, lightly flour the surface.
  6. Flatten the butter into a thin rectangle (approx. half the size of the dough) and place onto the dough.
  7. Fold the dough, close off the outer layer and roll out again.
  8. Fold the outer sides to the middle, fold the new outer sides to the middle. Rotate 90 degrees and fold double once more.
  9. Leave to rest in the fridge and repeat rolling and folding for two more times.
  10. Roll out the dough in a flat sheet (see photo higher up in the post) and cut into triangles. Roll the triangles (widest side first) into the croissant shape.
  11. Leave to rest for another hour.
  12. If desired, coat the croissants with a light egg wash, honestly, I never do this.
  13. Preheat the oven at 190C and bake for 10 minutes. Reduce the heat to 170C and bake for another 15 minutes.
  14. The croissants should be a nice light brown (not burned) and have expanded considerably.
  15. Enjoy!

Using poolish?

Poolish is a pre-ferment, this means it is part of your dough which has already had the chance to rise and thus develop flavour. A basic poolish is made with 100g water, 100g flour and 1 tsp instant yeast (you can decrease or increase amounts easily as long as you keep quantities the same). Leave this overnight (or during the day), it will start to bubble and rise a little. Add to your dough as required. It will often make your dough noticeably softer and delicate, such as in these French baguettes.

Folding technique photos

I do not (yet) have good photos of the folding and rolling process for making these croissants. The book from which I had the recipe (Brilliant bread) does, they’re great and easy to understand. I also like the photos from Sweet Phi, although their process seems a little more complicated than the one I mentioned (I don’t measure the height of my doughs…)

freshly baked mini croissants
Freshly baked mini French croissants, one has ham and cheese rolled inside, one of the many possible variations!

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