The smell of beurre noisette is probably one of my favorite smells. Whenever I cook up a big batch of it to keep for my cookie dough, it's almost impossible not to smile as its warm, nutty, and almost toffee-like aroma wafts through the air and into my nose. Making it is an extra step to take, but one that's definitely worth it if you want more flavor out of your butter!
The good thing about brown butter is it's relatively simple to make. You could cook it to a light brown for a mild flavor, or to a golden brown for something a little deeper. If you really wanted to, you could even go on the verge of almost burning it, to get the bold and almost bitter flavor of beurre noir or "black butter".
You can take it too far though, and quite easily too. I, for one, have accidentally cooked brown butter too far on several occasions. Like when caramelizing sugar, butter goes through many shades of brown, and the darker it gets, the faster it burns. Luckily, there are ways to make sure you don't end up with burnt butter! Skip ahead to learn how to make it, or keep reading to find out how those creamy yellow blocks get turned into toasty brown butter.
What is Butter?
People think of fat when they think about butter, but what a lot of people don't actually realize is that butter is an emulsion. Just like mayonnaise is an emulsion of egg yolks and oil, butter is an emulsion of water, fat, and milk solids.
When we churn cream to make butter, we're making a water-in-fat emulsion where the fat globules in the cream eventually clump together - trapping tiny droplets of water - until it solidifies into butter. What is then left of the cream is a thinner liquid called buttermilk that can be used for many things, like pancakes.
So as we can see, butter isn't just pure butterfat. It also contains water and milk solids - the latter of which allows us to make brown butter!
What is Brown Butter?
When you place butter in a saucepan and melt it, the water will eventually evaporate, and the emulsion we know as butter will break. You will see two distinct layers of separation - a white foam on top, which is the milk solids, and a golden yellow liquid on the bottom, which is the butterfat. At this point, you could let the layers settle, and later skim the white foam off of the top to get clarified butter.
Clarified butter is basically just butterfat. Since the milk solids have been removed, it's able to tolerate high heat better without burning. That makes it a good choice when sautéing or pan-frying, but it's also great to use for sauces like Hollandaise. With nothing mellowing down the taste of the butterfat, what you get is a rich and buttery flavor - but not the intense, nutty nuances of brown butter!
Unlike clarified butter, brown butter is cooked until the milk solids are toasty. If you continued to cook your butter without removing the white foam on top, that natural separation of milk solids would soon sink to the bottom of your saucepan. It wouldn't take long for those solids to undergo the Maillard reaction and brown, infusing the butterfat with a warm nutty flavor, and a golden-brown hue similar to the color of hazelnuts - which is why in French, it's called beurre noisette, or "hazelnut butter".
The Maillard Reaction
There are two ways in which food turns brown. The first is through enzymatic browning, which is browning that results from the oxidation of enzymes found in food, and is easy to see in sliced apples when they start to discolor. The second way is through non-enzymatic browning, of which there are two main forms - caramelization or the browning of sugars, and the Maillard (my-YARD or my-YAR) reaction.
First described in 1912 by the French chemist, Louis Camille Maillard, the Maillard reaction is essentially the browning of food as an effect of sugars reacting with amino acids - the building blocks of protein - at high temperatures. It is a very complex process of chemical reactions, and one that we don't really think about when we're toasting bread, searing steaks, and of course, browning butter.
It's also pretty incredible! The Maillard reaction not only causes a change in color, but also in flavor. Food contains different kinds and amounts of sugars and amino acids, and all of them react with each other when heated to create a multitude of flavor compounds distinct to that type of food. We're talking about hundreds of compounds that get broken down into even more flavor compounds as the Maillard reaction continues, progressing from a light to dark brown, and a mild to deep flavor.
In brown butter, the presence of milk solids makes it possible for the Maillard reaction to occur and create that hazelnut color and nutty flavor we love so much! These non-water components in milk are where we can find what we need: a sugar called lactose, and a protein called casein - a chain of several amino acids, the most important being lysine, which is the most reactive to sugar and easily produces the most color.
How Do You Make Brown Butter?
Now that you know a little more about the chemical reaction behind brown butter, I promise that it's going to be even more fun making it as you see the changes happening!
In the photos below, I'm cooking 2 kilos of butter with nonfat milk powder. This usually takes me around 30 minutes to an hour at low heat on my induction stove, but I like to cook up a big batch of brown butter because it saves me time when I need to make cookie dough. It's also harder to burn, and more forgiving if you happen to look away for longer than you think!
What You'll Need:
Saucepan (light-colored with a thick, heavy bottom)
Rubber Spatula (stiff and heatproof)
Unsalted Butter, cubed (not margarine or a butter blend!)
Optional: Nonfat Milk Powder - 5% of butter weight
What to Do:
Place your butter in a saucepan and melt over low heat. Cooking on low heat allows us to slow-roast the milk solids to get the most flavor we can out of it, and also keeps us from burning butter. Cutting your butter into roughly the same sizes will help it melt evenly. Adding milk solids in the form of nonfat milk powder will give you even more flavor, but only mix it in once all your butter has melted, or it may scorch on the bottom of your saucepan.
Your butter will separate to form a white foam on top (milk solids) and a yellow liquid underneath (butterfat) - this is a sign that the butter emulsion has broken. To make clarified butter, set your saucepan aside to let the layers settle, and skim off as much of the white foam as you can. Pass the clarified butter through several layers of cheesecloth to remove the rest of the milk solids.
To make brown butter, leave the foam on top, and continue cooking. Be careful and keep an eye on your butter! As it gets hotter, it will start to boil and the white foam on top will eventually sink. At this point, stir constantly - it's a good idea to use a rubber spatula with a stiff blade, so you can scrape off any bits stuck on the bottom of your saucepan without any trouble.
Keep stirring until the milk solids are toasted to your liking. As the milk solids cook, they will infuse color and flavor into the butterfat. The darker you go, the more intense and nutty the flavor will be - I like to cook mine to a golden brown! Using a light-colored, heavy saucepan allows you to easily check the color of the milk solids, and prevents any solids on the bottom from burning right away.
Remove your saucepan from the stove and transfer your brown butter to a heatproof container. Pouring your brown butter into another container will prevent it from cooking further. You can also keep your butter in your saucepan and just stop cooking when the milk solids are a touch lighter than you'd like. Keep in mind that smaller batches will cook and burn faster!
Let your brown butter cool, or use it right away. Read below on how to store and reheat your brown butter.
How to Store and Reheat Brown Butter
Storage
To store brown butter, I like to let it cool completely at room temperature before transferring it to the fridge. I let it chill just until the butterfat has thickened but not hardened, after which I give the whole thing a quick stir. This is an extra step that I like to do make sure I get equal amounts of butterfat and milk solids!
I then pour everything into an airtight container lined with parchment, before putting it back in the fridge. Parchment isn't necessary, but makes it easy to remove the butter from the container when you go take what you need. You can store your brown butter in the fridge for 2 to 3 weeks, or in the freezer for up to 3 months.
Reheating
Cut your butter into roughly the same sizes and melt on the stove or in a microwave. It's still possible to burn your butter, so keep your butter on low to medium heat.
What to Do With Brown Butter
Brown butter works very well on savory dishes, whether it be meat, fish, pasta, or vegetables. The main thing I use brown butter for is my cookie dough, but you can definitely use it for other baked goods as well!
Since we evaporate all the water when making brown butter, you'll need to adjust your recipe by adding some sort of liquid, like water or milk. Butter usually contains around 15% water. If your recipe calls for 150 grams, you could try substituting it with 128 grams of brown butter (85%) and 22 grams of liquid (15%). You may need to do a little tweaking though, since different butters contain different amounts of water!
References
Field, S. Q. (2012). Culinary Reactions. Chicago Review Press, Inc.
Kipfer, B. A. (2011). Butter. In The Culinarian: A Kitchen Desk Reference (p. 74). John Wiley & Sons, Inc.
Splawn, M. (2016, December 15). How To Brown Butter. The Kitchn. Retrieved May 2021, from https://www.thekitchn.com/how-to-brown-butter-238326
Fluid Milk Production. (n.d.). Milk Facts. Retrieved May 2021, from http://www.milkfacts.info/Milk%20Processing/Fluid%20Milk%20Production.htm
The Maillard Reaction. (2013, March 20). Modernist Cuisine. Retrieved May 2021, from https://modernistcuisine.com/mc/the-maillard-reaction/
Science of making brown butter sauce. (n.d.). Science of Cooking. Retrieved May 2021, from https://www.scienceofcooking.com/science-of-cooking-with-brown-butter.html