Dijon Mustard in Mac and Cheese: Why It Works

• Dijon mustard works as an emulsifier, helping the cheese sauce in mac and cheese stay smooth and creamy.
• Its tangy flavor balances rich dairy and starch, adding brightness that makes cheesy dishes more flavorful and satisfying.
• For the best results, whisk mustard in with the milk, taste often and adjust seasonings to your liking.

My mother enjoyed cooking and had a nice selection of cookbooks, but she juggled multiple jobs and didn’t have a lot of time to spend in the kitchen. Often, this meant that she’d pop something simple into the oven, disappear to her home office and re-emerge in the kitchen once the timer went off. Sometimes the food wasn’t done yet. Sometimes, it was a little extra crispy. Sometimes it was just right.

By the time I was a teenager, I’d taught myself to follow recipes using her collection of international cookbooks and helped out by making simple meals for our family of five. On mac and cheese night, though, my mom would always be the one stirring up the pot of gooey Mornay sauce, combining flour, butter, warm milk and shredded cheese into a delicious coating for slippery elbow noodles. And she always added one special ingredient to the mix: Dijon mustard.

Why Dijon Mustard? 

There are plenty of ingredients that can lend acidity to dishes, including citrus juices, vinegar, tomato and fermented dairy products, such as yogurt and buttermilk. However, Dijon mustard—which is made with ground seeds from mustard plants blended with either white wine vinegar or verjus, the juice of unripe grapes—has a culinary property that those others don’t: it’s an emulsifier.  

Emulsifiers contain molecules that bond to water on one side and fat on the other, which means they can help pull together sauces that otherwise might separate. Culinary emulsifiers include egg yolk and mustard and also items that are more likely to be found in manufacturing  plants than in your cupboard, such as lecithin, carrageenan and guar gum. Dijon mustard’s properties as an emulsifier are what make it such a key pantry ingredient. 

When Do You Blend It In? 

Mornay sauce, the French name for a creamy cheese sauce, is made by mixing up roux—a combo of fat and flour that’s used for thickening sauces and stews—and adding milk and grated cheese. Because vigorous stirring activates the emulsifying properties of mustard, my mom added it to the sauce along with the milk, which she whisked into the hot flour and butter in a steady stream. Once the sauce was thick and lump-free, she’d gently stir in the cheese.

How Does It Taste? 

In addition to its useful chemical properties, Dijon mustard simply tastes wonderful, with a hint of heat from the mustard seed and acidity from the vinegar. Because mac and cheese contains a lot of dairy and starch, these qualities of mustard help brighten the flavor and cut through the richness, making the dish extra mouthwatering. 

The truth is, I like a little more acidity in my cheese sauce than mom did, so cooks should adjust the amount of mustard used to suit their preferences. Start with a teaspoonful, and keep whisking in mustard until you notice that the flavor has gotten more complex and the tartness is detectable. Remember: you’ll be adding the cheese after, so you’ll probably need to make some final flavor adjustments once it’s melted. 

What Kind of Cheese Did Mom Use? 

Although mustard was a constant in my mom’s macaroni and cheese sauce, she’d vary the type of cheese depending on her mood and what we had in the house. Most of the time, extra-sharp Cheddar was her go-to, but she’d sometimes use super-melty Alpine-style fromages such as Gruyère or raclette. All of these work well with her “secret” ingredient.

She’d dollop this same sauce on other dishes, including a kielbasa, cabbage and potato combo that we ate regularly. In that case, she didn’t toss the ingredients with the sauce but put it on the table for us to spoon over the top.

Some Great Dijon Mustard Brands

Although Grey Poupon is well known thanks to its memorable commercials, the American version of the mustard isn’t the same as the European version and uses additional ingredients. Other brands that can be found throughout the US but are more true to the French style include Maille, Fallot and Pommery. I find that a brand with minimal ingredients works best in mac and cheese.

My Take on Mom’s Mac

Like my mom, I always mix Dijon mustard into my macaroni and cheese. For one thing, I love the way it thickens the sauce and binds it. For another, I almost always “season” food with both salt and acidic ingredients, and for this dish, mustard is my tangy mix-in of choice.

In addition to the aforementioned ingredients, I frequently add smoked paprika to my cheese sauces, along with freshly ground white or black pepper. Mom used a restrained hand with the grated cheese—probably because she was watching the budget—but I use lots and lots of grated, extra-sharp Cheddar or the same mix of Swiss cheeses that she liked. I’ve also made a variation that includes pepper Jack cheese and hot sauce. 

The Bottom Line

To make a creamy, emulsified cheese sauce with great flavor for your mac and cheese, whisk in a couple teaspoons of Dijon mustard when you’re adding the milk to the roux and before you stir in the cheese. For the best flavor, find a French mustard brand that has few ingredients. Taste several times as you make the sauce, and add extra mustard, salt and seasonings at the end of cooking to ensure that the mac and cheese is as delicious as can be.