Filled brioche donuts – A science guide for donuts

Making filled donuts can be a true hassle, trying to squirt some jam or creme patissiere into your donut, making sure not to add too much that it comes squirting out on the other side. As a result, I have never attempted a filled donut, too much trouble. But then I saw another great episode from British Bake Off. To be specific, one of their masterclass episodes in which Paul Hollywood made filled donuts by filling the donuts before even frying them. Ingenious!

The dough also seemed easy enough to work with, he used a brioche dough, great idea as well. So off we went, trying to replicate he filled brioche donuts. The recipes of the masterclasses can’t really be found online that easily, so I probably watched the section on donuts another 3 times, writing down the instructions and ingredients I needed. Also, watching carefully in how Paul handles the dough. There are a lot of tips and tricks that he doesn’t tell, but does show while he going along. So let’s discuss donuts and some proper donut science.

Cake vs Yeast donuts

Did you know there are two main ways to make a donut? And these are not new inventions, both methods have been around for decades. One method uses a yeast risen dough and they’re appropriately called yeast donuts or raised donuts. The other method though using baking powder and baking soda to puff up the donut. As a result, the cake donut tends to be a lot denser than a yeast donut. However, a cake donut can be made faster since it doesn’t require any proofing time, which the raised donut does.

Since baking powder and soda are pretty recent inventions, the yeast donut was most likely the first one to be developed. However, it was at a disadvantage from a time and processing perspective. It would take longer for bakers to make them and also, it proved to be harder to develop equipment for large scale equipment of yeast donuts that it was for the cake version. The yeast dough tended to be a little harder to handle. Probably thanks to their notable differences, both are still common and both can nowadays be manufactured at scale.

If you have a good look at the ingredients of the donut of your favorite donut store you will notice that they either contain yeast or baking powder/soda (look for a phosphate)! Here though, we’ll be sticking with yeast donuts.

chocolate covered and filled donuts on a tray
Chocolate covered (and filled) donuts.

Yeast brioche donuts

Within the yeast donut realm there are plenty of ways again to make donuts (e.g. sourdough, using a water roux). Not all methods make a dough that’s suitable for filling on forehand though. These doughs shouldn’t be too sticky, but soft enough to shape around a filling and strong enough to hold that filling inside.

Also, any donut dough should puff up properly once it’s fried to make a light, fluffy donut. A brioche dough happens to be great for that. A brioche dough is an enriched bread dough which means that it has butter and eggs added to the dough. The butter and eggs slow down the action of yeast, but also give it a very rich texture, it won’t taste dry easily.

Shaping & filling donuts

Once a yeast dough has been made and has proofed properly it should be shaped and filled into a donut! Some techniques ask you to roll out the dough and press out the donut shape (this one for instance). Others ask you to make a strand of dough, bring the two ends together and make a look like that. Others just say to make a ball of your dough. Donuts are flexible and so are the ways of making them. When choosing a way to shape them keep in mind the type of dough you’re using. Some doughs simply aren’t up for being made into a strand (not enough gluten/strength to hold it up) whereas others really can’t be rolled out (too sticky).

For these brioche filled donuts the dough is strong enough to shape into a cup, add the filling and close off the top again, but don’t try this with just any donut dough :-).

raspberry filled donut, not fully cooked
This donut is slightly underbaked/fried. The dough around the raspberry is still slightly fluid. It’s a balance of temperature and time. Using a frozen raspberry as a filling doesn’t make things easier either.

Why a lot of donuts have holes

Most donuts are the shape of a circle, with a hole in the middle. The main reason for this hole is to promote even and proper baking. The donut has a very large contact area with the oil so it’s quickly heated evenly. If the hole isn’t there it’s a bit more of a challenge to bake them properly. Whether that’s the reason the holes were introduced, nobody know. Some very funny and interesting stories can be found on the origin of donut holes (see bottom of post for an example).

Frying donuts (vs. baking)

Donuts are almost always fried in oil. Frying in oil goes very quick, the donut will be fully baked in a matter of minutes. This is because of the excellent heat transfer of the oil. The high temperature of the oil and the direct contact with the donut always help to expand the donut and become even more fluffy.

You can make donuts in the oven. It will take longer and they do tend to be less airy. They simply don’t expand as quickly and easily as the fried ones. Which, of course, doesn’t mean they don’t taste good, they’re just different :-).

These filled donuts won’t work well in the oven. It will be a lot harder to properly cook the center without the rest burning, due to the high butter and egg content.

Storing donuts

Interestingly, there’s very little information available online on the best way to store donuts. Apparently, everyone eats their donuts immediately… In order to determine the best way to store donuts, it’s useful to know how and why donuts become old, or less-fresh.

How donuts get old

If you leave a donut lying around on a plate for a while there is bound to be transfer of moisture. Moisture from within the donut will evaporate. Moisture from an icing may also evaporate, making the icing crispy instead of soft.

If you’ve got a sugar coated donut the sugar layer will absorb moisture from the donut and the environment. Sugar is quite hygroscopic, meaning it attracts moisture. This can cause the sugar to look a little more clumpy.

Also, as with any flour based bake, the donut will start staling. The process is actually very similar to that of bread and involves starches the recrystallize. Extra fat in the dough can delay the process though which is why donuts won’t be as stale as fast as a bread. The same goes for sourdough donuts, these also tend to stay fresh and moist for longer than their non-sourdough counterparts.

Any donut with a filling has an imbalance in it, especially if you’ve using a very moist (think fruit) filling. Since the center contains a lot of water and the dough doesn’t as much, the moisture will move from the center into the rest of the dough, making it soggy. In the case of a chocolate filling though there barely is any migration of the moisture and will thus keep easier. Some fillings (e.g. creme ones) need to be refrigerated to not spoil and keep their texture whereas others (e.g. that chocolate again) will cope well both in and out side of the fridge.

Storing donuts

These moisture migration and staling issues are pretty much irreversible. Therefore, eating the donuts fresh is always the best solution. But when you can’t, at least cover the donut up. Don’t do this in a completely closed plastic container, paper or a box work better here since they prevent moisture from sitting on your donut. However, this will make the donut dry out more quickly.

Storing donut dough

For the recipe at the bottom of this post you can freeze the donut dough at the point that the dough is just ready to start its last rise. When you take the dough balls out of the freezer again you’d have to thaw them. This will also slowly reactivate the yeast which sets in the last rise you need just before baking.

If you would have given them that last rise before frying they wouldn’t really be able to introduce any more air once they’ve been thawed and give less fluffy donuts.

filled donut dough balls ready to be rested and fried
Balls of donut dough, filled with chocolate filling, ready to be rested and then fried!

Filled brioche donut recipe

This recipe is based on the one from the Great British Bake Off masterclass series with a few tweaks and additions here and there. It’s a great recipe and not as much of a hassle to make as regular filled donuts.

chocolate filled donut with a bite out of it

Filled brioche donuts

  • Author: Science Chef
  • Prep Time: 75 mins
  • Cook Time: 30 mins
  • Total Time: 1 hour 45 mins
  • Yield: 18


  • 250g flour (bread flour or all purpose flour)
  • 1/8 tsp salt
  • 1 1/4 tsp instant yeast
  • 25g sugar
  • 2 eggs
  • 100ml milk
  • 125g butter (softened)


  • Choose a combination of the following, or don’t choose any and make plain donuts, those are also great!
  • Small fruits (e.g. raspberries, blueberries – you can use frozen ones, make sure you that them slightly (not completely!) one forehand and don’t take the excess liquid along when adding them into the dough)
  • Chocolate squares, each approx 5g
  • Oil for frying


  • Sugar
  • Chocolate (melted, you can use white, milk or dark)


Make the dough

  1. Add the flour, salt, yeast, sugar, eggs and milk into a stand mixer and knead until it has become a smooth sticky dough. Think of making a bread dough, you really need to develop the gluten.
  2. Add the softened butter to the mixture and continue mixing until all the butter has properly incorporated with the rest of the dough and there aren’t any butter pieces left.
  3. The dough is now very sticky as you will notice. It will be very hard to handle. That’s why you have to chill the dough properly, so the butter will set again. However, also take care that the yeast has a chance to do its thing. You can either put the dough in the fridge for 8 hours or leave it at room temperature for the first hour or so (to accelerate the yeast) before putting it in the fridge for another 5 hours. Other combinations and times will probably also work fine.

Making the donuts

  1. Take the dough from the fridge, it should be a lot firmer.
  2. Flatten the dough out and roll it up to make a long strand of dough. Split the strand of dough into 18 portions, they don’t have to be large, remember, they will puff up in the oil!
  3. Take a portion of dough, flatten it in your hand and add a bit of your filling. Close the ball up and roll it in your hands. You might need some extra flour here to prevent excessive sticking.
  4. Leave them (covered up) at room temperature for another 20-30 minutes or so. They should puff up slightly.
  5. Take a pan and fill it with just enough oil so the donuts can float in the oil. It’s best to not have to fill the pan more than halfway to prevent splashing.
  6. Heat the oil to 160-170C, don’t let it get hotter or the donuts will brown too quickly without being fully cooked.
  7. Fry the donuts 3-4 at a time (depending on the size of your pan). Flip them a few times until both sides are a nice golden brown. This should take about 3-5 minutes.
  8. If you used cold fruits, leave the donuts to rest a little longer before frying and be very careful not too over heat the oil. The cold and extra moisture makes it harder to cook the inside than for instance with a chocolate filling.


The masterclass episode from the Great British Bake Off

Want more donut inspiration? Serious Eats has a great long list of all sorts of donuts.

Cake Spy, Holey Grail: Why do donuts have holes, link; a great collection of possible backgrounds of the hole in the donut

RVO Info central, What is the difference between a yeast raised and cake donut?, link

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