Mac and Cheese Soup Recipe
This scientifically optimized Mac and Cheese Soup relies on a stable cheese emulsion and starch-coated pasta to deliver a velvety, rich texture that never splits.
- Sodium citrate in processed cheese prevents the cheese proteins from clumping and breaking under heat.
- Cooking the pasta directly in the broth releases starches that naturally thicken the soup base.
- A multi-tiered cheese blend balances sharp flavor development with optimal melting properties.
The secret to a flawless Mac and Cheese Soup lies in maintaining a stable emulsion between fats, proteins, and liquids. Traditional cheese sauces often break when heated to a boil, resulting in a grainy texture and a layer of oil on top.
This recipe prevents protein clumping by utilizing starch gelatinization.
When flour is cooked in butter to form a roux, the starch granules swell and absorb water, creating a physical barrier that keeps the proteins in the cheddar from bonding tightly and squeezing out fat. This is the same fundamental chemistry used to stabilize our Ale and Cheddar Soup. To further guarantee a velvety mouthfeel, we introduce a small amount of sodium citrate—naturally present in American cheese—which acts as an emulsifying salt to keep the fat suspended.
Selecting the right cheeses is equally critical for flavor and texture. Sharp cheddar provides the necessary acidity and depth, while Monterey Jack offers superior melting characteristics.
Unlike standard pasta dishes like Creamy Ham and Pea Pasta, the macaroni is cooked directly in the seasoned broth. This technique ensures the pasta absorbs maximum flavor while releasing its surface starches directly into the soup, reinforcing the liquid's viscosity.
Mac and Cheese Soup
Ingredients
- 4 tbsp unsalted butter
- 1/4 cup King Arthur all-purpose flour
- 1 medium yellow onion, finely diced
- 2 cloves garlic, minced
- 3 cups low-sodium chicken broth
- 2 cups whole milk
- 8 oz elbow macaroni, uncooked
- 8 oz sharp cheddar cheese, freshly grated
- 4 oz Monterey Jack cheese, freshly grated
- 2 oz processed American cheese, chopped
- 1 tsp dry mustard powder
- 1/2 tsp Diamond Crystal kosher salt
- 1/4 tsp freshly cracked black pepper
Directions
- Melt the unsalted butter in a heavy-bottomed Dutch oven over medium heat. Add the diced onion and cook for 5 minutes until translucent, then add the minced garlic and cook for 30 seconds until fragrant.
- Sprinkle the King Arthur all-purpose flour over the aromatics. Whisk constantly for 2 minutes to cook out the raw flour taste, allowing the mixture to turn a light golden color.
- Slowly pour in the chicken broth and whole milk in a steady stream, whisking vigorously to prevent lumps from forming. Bring the mixture to a gentle boil.
- Stir in the uncooked elbow macaroni, dry mustard powder, kosher salt, and black pepper. Reduce the heat to medium-low and simmer, stirring frequently to prevent the pasta from sticking to the bottom, for 8 to 10 minutes until the macaroni is al dente.
- Turn the heat to low. Add the grated sharp cheddar, Monterey Jack, and processed American cheese one handful at a time, stirring constantly until completely melted and smooth before adding the next batch. Do not allow the soup to boil once the cheese is added.
- Remove the pot from the heat. Let the soup rest for 3 minutes to thicken slightly before serving.
Notes
Always grate your own cheese from blocks to ensure a smooth, lump-free emulsion.
- Use Diamond Crystal kosher salt; if substituting Morton coarse kosher salt, reduce the volume by half (to 1/4 teaspoon) to avoid over-salting the delicate dairy base.
- Avoid pre-shredded bag cheeses because they are coated in cellulose or potato starch, which prevents clumping in the bag but disrupts the protein matrix during melting, resulting in a gritty, chalky soup texture.
- If you add the cheese while the soup is boiling, the high thermal mass will cause the proteins to denature and tighten into hard clumps, squeezing out the fat and breaking the emulsion. Prevent this by turning the burner to its lowest setting or removing the pot from the heat entirely before folding in the cheese.
- After 24 hours in the refrigerator, the pasta will continue to absorb liquid, causing the soup to lose its fluid consistency and turn into a thick, solid mass.
- If you do not have a heavy-bottomed Dutch oven, use a thick stainless steel stockpot, but reduce the heat slightly to prevent the milk solids from scorching on the thinner base.
Serving Suggestions
Complete this rich, comforting soup by introducing elements that offer textural contrast and bright acidity to cut through the heavy dairy profile.
- Top each bowl with crispy Grilled Cheese Croutons to add a satisfying crunch and double down on the toasted cheese flavor.
- Serve alongside a crisp green salad tossed in a sharp vinaigrette to cleanse the palate between rich spoonfuls.
- Garnish with finely chopped fresh chives or scallions to introduce a mild, sharp bite that cuts through the fat.
- Stir in a spoonful of roasted broccoli florets, similar to the flavor profile of our Roasted Broccoli and Cheddar Soup, for a woodsy, charred contrast.
Storage and Reheating
Store leftover soup in an airtight glass container in the coldest zone of your refrigerator for up to three days.
Do not freeze this soup. The freezing process breaks the delicate fat-and-water emulsion, and the pasta will turn mushy and disintegrate upon thawing.
To reheat, place the desired portion in a small saucepan over low heat. Whisk in two to three tablespoons of whole milk or chicken broth to restore the fluid consistency, stirring constantly to prevent scorching.
Alternatively, microwave in 30-second bursts at 50% power, stirring thoroughly between intervals to redistribute the heat and prevent the cheese from separating.
Ingredient Substitutes
You can swap several key ingredients in this recipe as long as you adjust your cooking technique to maintain the soup's structural integrity.
- Elbow Macaroni: Substitute with cavatappi or ditalini at a 1:1 ratio, but increase the simmer time by 2 minutes to account for the thicker pasta walls.
- Whole Milk: Substitute with a mixture of 1.5 cups 2% milk and 0.5 cups heavy cream to maintain the fat content; do not use skim milk as the lack of fat will cause the soup to split.
- Processed American Cheese: Substitute with 1/4 teaspoon of pure sodium citrate powder dissolved in the broth to achieve the same emulsifying power without altering the flavor profile.
Mastering this soup is a lesson in temperature control and emulsion stability. By respecting the delicate nature of cheese proteins, you will produce a consistently velvety bowl every time.