three flavors of creme patisserie

The Science of Creme Patissiere

It’s the cream of a pastry chef: creme patissiere, or creme pat in short. A fancy version of cream. It’s thick and creamy, and works well in a range of treats – what about filling some choux pastry with creme pat? Luckily, despite being a pastry chef’s cream, it’s not hard to make. On the contrary, once you know a few tips and tricks, it’s done in no time!

What is creme patissiere?

Creme patissiere, creme pat, or pastry cream, is a French delicacy. In French you’d write crème pâtissière, loosely translated as ‘cream of a pastry chef’. It’s not made with cream though. Instead, it’s thickened milk, with some added sugar for sweetness. You thicken the milk using flour and eggs, making it a sturdy version of a custard.

You’d generally use creme patissiere in cool or room temperature applications. You’d find it as a filling in choux pastry, or at the bottom of a fruit tart.

filling choux pastry with creme patissiere
Filling choux pastry with creme patissiere (a fruit-flavored version).

Eggs & flour thicken creme pat

So how come a creme patissiere is so nice and thick?

It’s all about balancing the effect of eggs and wheat flour. Both can thicken milk, but, when you use them together you have the benefits of both. Let’s have a look at eggs first.

Egg yolks thicken with proteins

You don’t use whole eggs to make creme pat, you just use the yolks, just like you do for a creme brulee for instance. The functional ingredients in egg yolks for pastry cream are fats, proteins, and lecithin. Fats help make the pastry cream creamy and rich. The lecithin helps to mix the water and fat, to create a smooth homogeneous texture. But it’s the proteins that thicken.

When egg yolk proteins are heated their properties change. They uncurl and take on a new shape that is better at holding onto water. By holding onto water, the overall mixture thickens.

Making egg-free creme patissiere?

You can make creme patissiere, or at least something that looks very much like it, without eggs. Instead of eggs, you could use corn starch, just like making eggless custard ice cream. Keep in mind that the texture will be different. It might be a little thicker, and less creamy and rich. You could overcome this by adding a little cream (which contains a lot of fat).

When replacing eggs, start by replacing 1 egg yolk with 2 tsp of corn starch.

Flour thickens with starch

Flour on the other hand barely contains any fat. Instead, flour contains a lot of carbohydrates, more specifically: starches. Starches are very good at thickening liquids. When you heat starches mixed with water they gelatinize. That is, the starches absorb a lot of water and release a lot of those water absorbing molecules that all hold onto water.

Since flour doesn’t contain fats, liquids thickened with flour are less rich and creamy. But, flour is a very effective thickener. You need less flour than egg yolk to reach the same thickness.

Creme pat isn’t the only food that uses wheat flour for thickening. There are many more. Bechamel sauce is another example, as well as donuts made with water roux or even choux pastry.

Substituting flour?

Instead of using flour, you may find that some recipes will use some sort of starch, such as potato or corn starch. This works in a very similar way. The starches will also thicken the mixture.

You can decide to substitute both the flour and the egg with corn starch. However, the texture of the creme pat will be different. It’s still a custard, and it’s still thick though, so feel free to experiment!

water roux: heating and thickening
A water roux made with just water & flour. Notice how thick the mixture has become?

How to make creme pat

Making creme patissiere, or pastry cream, takes just a few steps. It’s not complicated, but it is important that you do things in the right order, or you’d end up with a lumpy version.

Remember that making pastry cream is all about thickening the milk. Both the egg yolks and the flour can thicken. However, both should be handled carefully. Egg yolks may scramble, or curdle. Flour can form lumps. So making a creme pat is all about ensuring they can thicken the milk, without showing these undesirable side effects!

Let’s have a look at how to do so.

Step 1: Mix egg, sugar and flour

The best way to prevent lumping of flour is to mix it with a cold liquid. When that liquid is still cold, the flour won’t gelatinize yet. As such, you can easily mix it in. If you mix flour with a hot liquid though, the outside of flour particles will gelatinize very quickly. As a result, the particles don’t have time to mix properly. The dry inside will be trapped within the thickened gelatinized layer.

When making pastry cream, mix the egg yolks and sugar first. This loosens up the egg and makes it easier to then mix in the flour as well. It should be easy to make a smooth batter!

Step 2: Heat milk

Egg yolks are prone to overcooking. As such, you’d want to heat them gently. However, that can take a long time.

So, what you do instead, is heat up the milk. You can heat up milk quite rapidly, without any challenges – just be sure it doesn’t boil over! Once it’s hot, you can use it to ‘temper’ the eggs. That is, you pour the hot milk into the egg mix. That way, the eggs + flour + sugar mixture starts to heat, without overcooking.

It’s important that you mix the eggs, while adding the hot milk. You don’t want any local hot spots that could overcook the eggs. Egg yolks start to cook at about 60-70°C. As long as you continue whisking while adding the milk, the final temperature of the mix will remain lower than the temperature at which they cook.

filled profiterole, ready to eat
The profiteroles are filled, the creme patissier oozes out a little, jum!

Step 2b (optional): Add flavor

Some recipes also use this step to infuse flavor. Add in a vanilla bean, some ground coffee, or spices and let them sit in the warm milk for some time. The flavor molecules from these ingredients will slowly seep into the milk. This happens a lot faster in hot milk, than it does in cold!

Just before you’d use the milk, just sieve out the added ingredients and quickly re-heat the milk before pouring it onto the eggs.

Step 3: ‘Cook’ the egg + milk mix

Last, but not least, it’s time to actually put the flour and egg yolks to work!

It’s time to continue heating the warm mixture of egg, sugar, flour, and milk. Since the mix is already warm, this final step won’t take long. But, it is important that it’s stirred continuously. Thickening will happen quite rapidly and if you don’t stir, you’ll still end up with clumps of pastry cream that have thickened too fast.

When determining whether your creme patissiere is done, keep in mind that it will thicken when it cools down! The starches in the flour especially will continue to absorb some water. And, at lower temperatures, the molecules in the creme pat just aren’t as mobile anymore, causing it to thicken further.

Step 3b (optional): Add flavor

There’s another opportunity to add flavor to your creme patissiere, right at the end. Creme pat is quite a resilient product. It can handle quite a lot of additions. For instance, you could add flavor extracts, or some cocoa powders. You could even add some fruit jams or pastes. Just keep in mind that anything with a lot of water will change the consistency of the pastry cream, making it thinner.

Once your creme patissiere has cooled down, it’s ready to use! How about using it to fill choux pastry, in a fruit tart, or as a donut filling? Or, how about trying to make your own? You have all the knowledge you should need now! Try varying the ratios of milk, sugar, eggs, and flour to make your optimal pastry cream. There’s no one perfect recipe. Everyone will prefer something slightly different.

three flavors of creme patisserie

Creme Patissiere / Pastry Cream

Prep Time: 5 minutes
Cook Time: 15 minutes
Total Time: 20 minutes

You can tweak this basic creme patissiere recipe with a variety of flavors, or colors, to make one you like. We provide suggestions for both plain as well as flavored versions.

Don't skip the step of premixing the eggs with the sugar & flour. This ensures you don't end up with lumpy pastry cream!


  • 250ml milk
  • 2 egg yolks
  • 25g sugar
  • 12,5g flour (approx. 1,5 tbsp)


  • 3 tbsp cocoa powder OR
  • few drops of pandan paste OR
  • 1/2 tsp vanilla extract


  1. Mix the egg yolks, sugar, and flour in a bowl until it's a smooth paste, without any lumps.
  2. Bring the milk to a boil in a pot.
  3. Carefully pour the hot milk into the egg mixture while whisking it. This ensures that the eggs start to heat, without curdling.
  4. Pour the mixture back into the pot and gently heat it on the stovetop while stirring continuously.
  5. The mixture will start to thicken quite rapidly. Once it has thickened, turn of the heat and leave it to cool.
  6. If using one of the optional ingredients. Mix them in now. Taste to decide whether you want to add a little more. If you'd like several flavors, just split your batch of pastry cream in smaller portions and flavor each one with a different flavor.
  7. Whisk through the creme patissiere a few more times while it's cooling or cover tightly with a lid to ensure the top doesn't dry out.


This portion made enough to fill 15 small choux pastry buns or 8 large ones. Of course, it all depends on the size of your buns and how much filling you want to add.

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  1. Isn’t this the same as making a custard? Is there any specific difference between the two like maybe the ratio in which the ingredients are taken?

    • Hi Shriya,
      Yes, the two are very similar indeed. There are some differences though (although they do differ per person and definition, as always!). Most custards won’t use flour, but get all of their thickening from the eggs (although corn starch is used as well once in a while). All in all, this creme patisserie is a little thicker than most custards (due to the flour). If you want a light, silky custard reduce the flour or remove it, this will make it a little trickier to thicken it properly since you fully depend on the eggs.
      Hope that helps!

  2. I had a filled donut that seemed soft and creamy rather than the somewhat gelatinous texture you’d find in a Boston cream. Would that be achieved by reducing flour and maybe cooking longer for thickness?

    • Hi Robin,

      Great question! There are a lot of ways to make fillings for donuts apart from using creme patissiere. They might have also used a stabilized whipped cream for instance (which will be airier as well though). Some recipes also use a custard instead of creme patissiere, custard has a slightly different texture as well and doesn’t use flour but does tend to be a little more runny.
      Reducing flour does reduce the gelatinous texture, however, it might also become less stable and too liquid and runny. Cooking longer definitely increase thickness since there’s just less moisture as well.

      Hope that helps!

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