Cinnamon french toast with icing sugar and grapes

The Science of Cinnamon French Toast (+ Recipe)

Back in the 2nd grade of high school we had a few cooking classes during the year. It surely wouldn’t suffice to become a good cook, most dishes were pretty simple, but I do still vividly remember the first thing I learned to make in that class: French Toast. Of course, I had to try to recipe at home loads of times at well, it served great for breakfast or lunch and I thought it was fun to make.

Why we were taught how to make French Toast (or wentelteefjes [when-tul-tave-yes] in Dutch) I wouldn’t know. It isn’t really a super essential thing to know how to make, but I guess students liked it so it helped us stay interested. Nowadays though, I would love to teach a class how to make French Toast. Of course though, they’ll get a free science lesson to go with it ;-), as is the case in this post of well. The science of making cinnamon French Toast.

What’s French toast?

In it’s purest form French toast is bread, soaked in milk and egg which has been fried in a frying pan. Although even that description might be too limiting, since older versions seemed to have used other liquids for soaking the bread.

As with any non-recent food it’s hard to say where french toast came from and whether it’s actually French. But that doesn’t make it an any lesser dish. Personally, I would have thought French toast was invented by someone or several people who didn’t want to eat old stale bread, but didn’t want to throw it out either. Soaking the bread and then baking it certainly makes it a lot more palatable again.

So let’s have a look to see what happens when making French toast.

The Bread – using left overs

Just about any bread that keeps together well can be used for making french toast (you don’t want one that falls apart almost immediately after soaking). However, the best bread for French Toast in my opinion is bread that has gone stale and old. Not only does it absorb moisture better and seem to hold onto it better, it also reduces the amount of food waste, win/win!

Online various debates can be found as to which bread is best for making French Toast. Of course, just using bread you have in your home would be best, who’d buy a fresh loaf especially for French Toast? Personally, I prefer to use plain, cheap bread for making French Toast. Bread that doesn’t taste best by itself and can do with some improvements, like turning it into French toast. That said, I did find that Brioche or Challah bread (both less plain and richer in flavour) are used very often as well.

When bread stales it will become drier and tougher. This is due to several processes occurring at the same time (read all about staling of bread). One of these reasons is the loss but especially reorganization of moisture inside the slice. By soaking the bread in an egg/milk batter (which we’ll discuss in a little while), all of the bread becomes moist again. The bread structure will readily absorb the moisture. Bread also stales because of retrogradation of starch. We know that we can reverse this by reheating the bread, when baking this French toast that is bound to happen, at least partly, as well.

making french toast, the batter and bread

The Batter

The most basic batter for French toast would be a mixture of eggs and milk. It’s these two that will determine the final structure of the French toast, will it be soggy, firm, cripsy or dry?


Let us start by having a look at the eggs. The eggs are what keeps everything together. When eggs are cooked the proteins will denature and form a strong network. You can see this when boiling or frying an egg. In french toast enough eggs have to be present to set the milk that is added. You do not want all the milk seeping out of the toast.


Theoretically you could make french toast without any milk. You would make an omelette in bread. Milk is what makes the french toast softer. The bread will soak up the milk and become nice and soft. The milk proteins react with sugar in the browning reactions and milk fat gives the french toast a slightly richer structure.

The extra’s

There are a lot of other ingredients you can add for flavour. In the recipe below you will find sugar and cinnamon. These don’t really contribute to the overall texture, but do spice things up flavourwise. Sugar can also speed up caramelization, leading to quicker browning of the French Toast. A quick google search will give you plenty of other ideas.

Tweaking the recipe

Since there’s only a limited amount of ingredients that actually influence the results, there are loads of pretty easy ways to tweak the recipe to your liking. Wouldn’t it be great to test all of these out in a 2nd grade high school cooking class?!

  • Firmer texture: add more egg or less milk, the more egg you add the more the structure will be like that of an omelet
  • Soggier/softer texture: add less eggs or more milk, the less egg you add the more liquid the french toast becomes; another option is to use bread that is sliced thicker, the inside will be harder to cook completely staying softer
  • Browner colour: add more sugar to get more browning reactions going on
  • More crispy outside: adding more sugar can help here by forming a caramel like crust, less milk can help as well; take thinner sliced bread, it is easier to fully cook this slice, bread cannot get crispy if there still is a lot of moisture

The toppings

Once this cinnamon french toast is ready, it’s time to eat in. Personally, I eat my french toast with icing sugar, sugar syrup or some sort of chocolate topping (sprinkels or spread). Also, I like combining it with fresh fruits to make it a more complete breakfast.

However, opinions matter, I noticed for instance that some people like theirs with tomato ketchup… Tastes differ, so do whatever you like!french toast with tomato ketchup

Cinnamon French Toast Recipe

Use this french toast recipe as a starting point, but as mentioned above, do play around with it. It’s a simple way to start experimenting with your cooking. Also keep in mind that different breads, different slice thickness, etc. will impact the required amount of batter. Adjust where required.

Cinnamon french toast with icing sugar and grapes

Science of cinnamon French Toast

Yield: 6 slices
Prep Time: 5 minutes
Cook Time: 15 minutes
Total Time: 20 minutes


  • 1 egg
  • 200 ml milk (if you like it eggier, leave out some of the milk and keep back a slice of bread)
  • 1/4 tsp cinnamon
  • 1 tsp sugar
  • 6 slices of bread (approx. 0,5cm thick)


  1. Mix the eggs and the milk in a bowl until the eggs have been mixed through well.
  2. Add the cinnamon and sugar and whisk quickly .
  3. Take the slices of bread and soak them in the mixture one by one, this should only take a few seconds with these thinner slices of bread. Stack the slices on top of one another.
  4. Heat a little butter in a frying pan.
  5. Once the pan is hot, add the soaked slices bread. If the lowest slice becomes too soaked, turn around the stack to assure the not all liquid seeps to the bottom.
  6. Turn the slice once the bottom has browned slightly and comes of easily. Fry both sides until thy are brown. Keep the pan at a low to medium heat, avoid the high heat, this can cause the outside to brown whereas the inside stays soggy and undercooked.
Newsletter subscription box


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

  • Skip the milk and do not soak. A few seconds is enough. It won’t end up like an omelette as mentioned above, and you will end up with a nice firm french toast without the dreaded soggy/custardy center. Soggy french toast is always a sign of over-soaking.

    • Hi, Thanks for that addition. It makes a lot of sense not to soak for too long indeed, especially with thick slices where cooking that center is so challenging!

  • I use heavy cream instead of milk. The rich density gives it not only flavor but a nicer texture when its cooked thoroughly. The bread seems to rise a bit. I also use vanilla extract as my sweetener. Just a little drop or two for 2 eggs and 3-4oz heavy cream. If I really am craving sweet I crush up Graham crackers and after dipping the bread in the egg mixture I the coat it with a dusting of the Graham crackers and oh my goodness are they yummy with some yogurt and strawberries!

sign up for a food sceince course
Find a book to read