Cheddar Cheese Soup with Dijon Mustard

This cheddar cheese soup is pure comfort in a bowl. Sharp cheddar provides a bold, tangy cheese flavor, while Dijon mustard adds a subtle kick that cuts through the richness. Scattered throughout are crispy bits of smoked ham that add texture and savory depth. It's the kind of soup that makes cold days feel cozy and warm.

The Perfect Cheese for Soup

Not all cheddar is created equal, especially when it comes to soup. The cheese you choose will determine the soup's character, so choose wisely.

Sharp or extra-sharp cheddar is essential here. Mild cheddar simply won't have enough flavor to stand out against the mustard and ham. Look for cheddar aged at least 9-12 months for the best balance of flavor and meltability. Very old, crumbly cheddars (2+ years) have incredible flavor but can be harder to melt smoothly.

Grate your own cheese. This makes an enormous difference. Pre-shredded cheese is coated with anti-caking agents (usually potato starch or cellulose) that prevent smooth melting and can make your soup grainy. It takes an extra minute but the result is incomparably better.

Consider a cheese blend. For more complex flavor, mix your cheddar with other good melting cheeses: Gruyère adds nuttiness, smoked Gouda adds depth, or a bit of cream cheese adds extra smoothness.

The Role of Dijon Mustard

Mustard might seem like an unusual addition to cheese soup, but it's actually a classic pairing. The combination appears in Welsh rarebit, fondue, and mac and cheese for good reasons:

• Cuts through richness: The acidity and sharpness of mustard balance the heavy cheese
• Enhances cheese flavor: Mustard contains compounds that make cheese taste "cheesier"
• Aids emulsification: Mustard helps keep the cheese suspended in the liquid
• Adds complexity: The flavor mellows during cooking, leaving pleasant depth

Don't worry about the soup tasting like mustard—the flavor integrates and rounds out, becoming an indistinguishable part of the overall taste.

Getting Silky-Smooth Texture

The biggest challenge with cheese soup is achieving that perfectly smooth, creamy texture without any graininess. Here's how to guarantee success:

The roux is your friend. The butter-flour mixture does more than thicken—it helps emulsify the cheese into the liquid, creating a stable, smooth soup. Cook the roux just until it loses its raw flour smell, about 2 minutes.

Temperature is critical. Never add cheese to boiling liquid. The proteins in cheese tighten when overheated, squeezing out fat and creating a grainy, separated mess. Always remove the pot from heat before adding cheese.

Add cheese gradually. Adding all the cheese at once can cool the liquid too quickly, preventing proper melting. Add it in small handfuls, stirring until each addition is incorporated before adding more.

Stir constantly. Keep the soup moving as the cheese melts to ensure even distribution and prevent any cheese from clumping at the bottom.

Why Leeks Instead of Onions?

Leeks bring a milder, more refined allium flavor than onions. They're sweeter and less pungent, which lets the cheese remain the star. Their soft texture when sautéed also integrates beautifully into the soup. If you can't find leeks, substitute with a combination of sweet onion and a few chives.

The Crispy Ham Factor

Don't skip the ham—it's what takes this soup from good to great. Frying the ham until the edges turn crispy creates wonderful textural contrast against the smooth soup. The smoky, salty bits also add flavor depth that plain cheese soup lacks.

For the best results, use thickly sliced deli ham or leftover holiday ham cut into strips. Fry in a single layer without crowding the pan, and don't stir too much—let the pieces develop a golden crust before flipping.

Serving Suggestions

This soup is substantial enough for a light meal on its own, but here are ways to round it out:

• Crusty bread: A warm baguette or sourdough for dipping is essential
• Over baked potatoes: Ladle the soup over split potatoes for a loaded experience
• With vegetables: Steam broccoli, cauliflower, or asparagus and use the soup as a sauce
• Simple green salad: Something acidic like a salad with vinaigrette balances the richness

Variations to Try

Beer cheese soup: Replace 1 cup of broth with a light lager or amber ale for a pub-style version.

Broccoli cheddar: Add 2 cups of chopped broccoli florets to the simmering soup until tender, then proceed with the cheese.

Loaded baked potato style: Top individual servings with sour cream, chopped chives, and extra crispy bacon.